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Sample records for cooper pairing gaps

  1. Junctionless Cooper pair transistor

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunov, K. Yu., E-mail: konstantin.yu.arutyunov@jyu.fi [National Research University Higher School of Economics , Moscow Institute of Electronics and Mathematics, 101000 Moscow (Russian Federation); P.L. Kapitza Institute for Physical Problems RAS , Moscow 119334 (Russian Federation); Lehtinen, J.S. [VTT Technical Research Centre of Finland Ltd., Centre for Metrology MIKES, P.O. Box 1000, FI-02044 VTT (Finland)

    2017-02-15

    Highlights: • Junctionless Cooper pair box. • Quantum phase slips. • Coulomb blockade and gate modulation of the Coulomb gap. - Abstract: Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous 'slip' of the phase by ±2π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current–voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.

  2. Junctionless Cooper pair transistor

    Science.gov (United States)

    Arutyunov, K. Yu.; Lehtinen, J. S.

    2017-02-01

    Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous 'slip' of the phase by ±2π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current-voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.

  3. Cooper pairs and bipolarons

    OpenAIRE

    Lakhno, Victor D.

    2016-01-01

    It is shown that Cooper pairs are a solution of the bipolaron problem for model Fr\\"{o}hlich Hamiltonian. The total energy of a pair for the initial Fr\\"{o}hlich Hamiltonian is found. Differences between the solutions for the model and initial two-particle problems are discussed.

  4. Cooper pairs and bipolarons

    Science.gov (United States)

    Lakhno, Victor

    2016-11-01

    It is shown that Cooper pairs are a solution of the bipolaron problem for model Fröhlich Hamiltonian. The total energy of a pair for the initial Fröhlich Hamiltonian is found. Differences between the solutions for the model and initial two-particle problems are discussed.

  5. Excited cooper pairs

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Arrietea, M. G.; Solis, M. A.; De Llano, M. [Universidad Nacional Autonoma de Mexico, Mexico, D.F (Mexico)

    2001-02-01

    Excited cooper pairs formed in a many-fermion system are those with nonzero total center-of mass momentum (CMM). They are normally neglected in the standard Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity for being too few compared with zero CMM pairs. However, a Bose-Einstein condensation picture requires both zero and nonzero CMM pairs. Assuming a BCS model interaction between fermions we determine the populations for all CMM values of Cooper pairs by actually calculating the number of nonzero-CMM pairs relative to that of zero-CMM ones in both 2D and 3D. Although this ratio decreases rapidly with CMM, the number of Cooper pairs for any specific CMM less than the maximum (or breakup of the pair) momentum turns out to be typically larger than about 95% of those with zero-CMM at zero temperature T. Even at T {approx}100 K this fraction en 2D is still as large as about 70% for typical quasi-2D cuprate superconductor parameters. [Spanish] Los pares de cooper excitados formados en un sistema de muchos electrones, son aquellos con momentos de centro de masa (CMM) diferente de cero. Normalmente estos no son tomados en cuenta en la teoria estandar de la superconductividad de Bardeen-Cooper-Schrieffer (BCS) al suponer que su numero es muy pequeno comparados con los pares de centro de masa igual a cero. Sin embargo, un esquema de condensacion Bose-Einstein requiere de ambos pares, con CMM cero y diferente de cero. Asumiendo una interaccion modelo BCS entre los fermiones, determinamos la poblacion de pares cooper con cada uno de todos los posibles valores del CMM calculando el numero de pares con momentos de centro de masa diferente de cero relativo a los pares de CMM igual a cero, en 2D y 3D. Aunque esta razon decrece rapidamente con el CMM, el numero de pares de cooper para cualquier CMM especifico menor que el momento maximo (o rompimiento de par) es tipicamente mas grande que el 95% de aquellos con CMM cero. Aun a T {approx}100 K esta fraccion en 2D es

  6. P-wave Cooper pair splitting

    Directory of Open Access Journals (Sweden)

    Henning Soller

    2012-07-01

    Full Text Available Background: Splitting of Cooper pairs has recently been realized experimentally for s-wave Cooper pairs. A split Cooper pair represents an entangled two-electron pair state, which has possible application in on-chip quantum computation. Likewise the spin-activity of interfaces in nanoscale tunnel junctions has been investigated theoretically and experimentally in recent years. However, the possible implications of spin-active interfaces in Cooper pair splitters so far have not been investigated.Results: We analyze the current and the cross correlation of currents in a superconductor–ferromagnet beam splitter, including spin-active scattering. Using the Hamiltonian formalism, we calculate the cumulant-generating function of charge transfer. As a first step, we discuss characteristics of the conductance for crossed Andreev reflection in superconductor–ferromagnet beam splitters with s-wave and p-wave superconductors and no spin-active scattering. In a second step, we consider spin-active scattering and show how to realize p-wave splitting using only an s-wave superconductor, through the process of spin-flipped crossed Andreev reflection. We present results for the conductance and cross correlations.Conclusion: Spin-activity of interfaces in Cooper pair splitters allows for new features in ordinary s-wave Cooper pair splitters, that can otherwise only be realized by using p-wave superconductors. In particular, it provides access to Bell states that are different from the typical spin singlet state.

  7. Amplification of Cooper pair splitting current in a graphene-based Cooper pair beam splitter geometry

    Science.gov (United States)

    Islam, SK Firoz; Saha, Arijit

    2017-09-01

    Motivated by the recent experiments [Scientific Reports 6, 23051 (2016), 10.1038/srep23051; Phys. Rev. Lett. 114, 096602 (2015), 10.1103/PhysRevLett.114.096602], we theoretically investigate Cooper pair splitting current in a graphene-based Cooper pair beam splitter geometry. By considering the graphene-based superconductor as an entangler device, instead of normal [two-dimensional (2D)] BCS superconductor, we show that the Cooper pair splitting current mediated by the crossed Andreev process is amplified compared to its normal superconductor counterpart. This amplification is attributed to the strong suppression of the local normal Andreev reflection process (arising from the Cooper pair splitting) from the graphene-based superconductor to lead via the same quantum dot, in comparison to the usual 2D superconductor. Due to the vanishing density of states at the Dirac point of undoped graphene, a doped graphene-based superconductor is considered here and it is observed that Cooper pair splitting current is very insensitive to the doping level in comparison to the usual 2D superconductor. The transport process of nonlocal spin-entangled electrons also depends on the type of pairing, i.e., whether the electron-hole pairing is onsite, intersublattice or the combination of both. The intersublattice pairing of graphene causes the maximum nonlocal Cooper pair splitting current, whereas the presence of both pairings reduces the Cooper pair splitting current.

  8. Induced spectral gap and pairing correlations from superconducting proximity effect

    Science.gov (United States)

    Chiu, Ching-Kai; Cole, William S.; Das Sarma, S.

    2016-09-01

    We theoretically consider superconducting proximity effect, using the Bogoliubov-de Gennes (BdG) theory, in heterostructure sandwich-type geometries involving a normal s -wave superconductor and a nonsuperconducting material with the proximity effect being driven by Cooper pairs tunneling from the superconducting slab to the nonsuperconducting slab. Applications of the superconducting proximity effect may rely on an induced spectral gap or induced pairing correlations without any spectral gap. We clarify that in a nonsuperconducting material the induced spectral gap and pairing correlations are independent physical quantities arising from the proximity effect. This is a crucial issue in proposals to create topological superconductivity through the proximity effect. Heterostructures of three-dimensional topological insulator (TI) slabs on conventional s -wave superconductor (SC) substrates provide a platform, with proximity-induced topological superconductivity expected to be observed on the "naked" top surface of a thin TI slab. We theoretically study the induced superconducting gap on this naked surface. In addition, we compare against the induced spectral gap in heterostructures of SC with a normal metal or a semiconductor with strong spin-orbit coupling and a Zeeman splitting potential (another promising platform for topological superconductivity). We find that for any model for the non-SC metal (including metallic TI) the induced spectral gap on the naked surface decays as L-3 as the thickness (L ) of the non-SC slab is increased in contrast to the slower 1 /L decay of the pairing correlations. Our distinction between proximity-induced spectral gap (with its faster spatial decay) and pairing correlation (with its slower spatial decay) has important implications for the currently active search for topological superconductivity and Majorana fermions in various superconducting heterostructures.

  9. Cooper pairs spintronics in triplet spin valves.

    Science.gov (United States)

    Romeo, F; Citro, R

    2013-11-27

    We study a spin valve with a triplet superconductor spacer intercalated between two ferromagnets with noncollinear magnetizations. We show that the magnetoresistance of the triplet spin valve depends on the relative orientations of the d vector, characterizing the superconducting order parameter, and the magnetization directions of the ferromagnetic layers. For devices characterized by a long superconductor, the effects of a polarized current sustained by Cooper pairs only are observed. In this regime, a supermagnetoresistance effect emerges, and the chiral symmetry of the order parameter of the superconducting spacer is easily recognized. Our findings open new perspectives in designing spintronics devices based on the cooperation of ferromagnetic and triplet correlations.

  10. Breaking of Cooper pairs in 108Pd

    Science.gov (United States)

    Rahmatinejad, A.; Kakavand, T.; Razavi, R.

    2016-04-01

    In this paper, breaking of Cooper pairs in 108Pd is investigated within the canonical ensemble framework and the BCS model. Our results show an evidence of two phase transitions, which are related to neutron and proton systems. Also, with consideration of pairing interaction, the role of neutron and proton systems in entropy, spin cutoff parameter and as a result in the moment of inertia are investigated. The results show minor role for the proton system at low temperatures and approximately equal roles for both neutron and proton systems after the critical temperature. Good agreement was observed between obtained results and the experimental data.

  11. Momentum Dependence of Superconducting Gap, Strong-Coupling Dispersion Kink, And Tightly Bound Cooper Pairs in the High-T(C)(Sr,Ba)(1-X)(K,Na)(X)Fe(2) As(2) Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wray, L.; Qian, D.; Hsieh, D.; Xia, Y.; Li, L.; Checkelsky, J.G.; Pasupathy, A.; Gomes, K.K.; Parker, C.V.; Fedorov, A.V.; Chen, G.F.; Luo, J.L.; Yazdani, A.; Ong, N.P.; Wang, N.L.; Hasan, M.Z.

    2009-05-28

    We present a systematic angle-resolved photoemission spectroscopic study of the high-T{sub c} superconductor class (Sr/Ba){sub 1-x}K{sub x}Fe{sub 2}As{sub 2}. By utilizing a photon-energy-modulation contrast and scattering geometry we report the Fermi surface and the momentum dependence of the superconducting gap, {triangle}(k{open_square}). A prominent quasiparticle dispersion kink reflecting strong scattering processes is observed in a binding-energy range of 25--55 meV in the superconducting state, and the coherence length or the extent of the Cooper pair wave function is found to be about 20 {angstrom}, which is uncharacteristic of a superconducting phase realized by the BCS-phonon-retardation mechanism. The observed 40{+-}15 meV kink likely reflects contributions from the frustrated spin excitations in a J{sub 1}-J{sub 2} magnetic background and scattering from the soft phonons. Results taken collectively provide direct clues to the nature of the pairing potential including an internal phase-shift factor in the superconducting order parameter which leads to a Brillouin zone node in a strong-coupling setting.

  12. Rotochemical heating in millisecond pulsars with Cooper pairing

    CERN Document Server

    Petrovich, Cristobal

    2010-01-01

    When a rotating neutron star loses angular momentum, the reduction in the centrifugal force makes it contract. This perturbs each fluid element, raising the local pressure and originating deviations from beta equilibrium that enhance the neutrino emissivity and produce thermal energy. This mechanism is named rotochemical heating and has previously been studied for neutron stars of non-superfluid matter, finding that they reach a quasi-steady state in which the rate that the spin-down modifies the equilibrium concentrations is the same to that of the neutrino reactions restoring the equilibrium. On the other hand, the neutron star interior is believed to contain superfluid nucleons, which affect the thermal evolution of the star by suppressing the neutrino reactions and the specific heat, and opening new Cooper pairing reactions. In this work we describe the thermal effects of Cooper pairing with spatially uniform energy gaps of neutrons and protons on rotochemical heating in millisecond pulsars (MSPs) when on...

  13. Nuclear Pairing from Two-body Microscopic Forces: Analysis of the Cooper Pair Wavefunctions

    CERN Document Server

    Finelli, P; Holt, J W

    2014-01-01

    In a recent paper we studied the behavior of the pairing gaps $\\Delta_F$ as a function of the Fermi momentum $k_F$ for neutron and nuclear matter in all relevant angular momentum channels where superfluidity is believed to naturally emerge. The calculations employed realistic chiral nucleon-nucleon potentials with the inclusion of three-body forces and self-energy effects. In this contribution, after a detailed description of the numerical method we employed in the solution of the BCS equations, we will show a preliminary analysis of the Cooper pair wavefunctions.

  14. Can Cooper pairs in benzene lead to Efimov states?

    Science.gov (United States)

    Squire, R. H.; March, N. H.; Rubio, A.

    2015-02-01

    Cooper pairs have been experimentally verified in benzene at 38.3 eV. We have proposed previously that the six most loosely bound electrons in benzene form three equivalent Cooper pairs. We further propose in this manuscript that these three weakly interacting bosons (Cooper pairs) should form an infinite number of Efimov states (possibly Booromean rings) which is what a photon of high energy will then encounter.

  15. Drive the Dirac electrons into Cooper pairs in SrxBi2Se3

    Science.gov (United States)

    Du, Guan; Shao, Jifeng; Yang, Xiong; Du, Zengyi; Fang, Delong; Wang, Jinghui; Ran, Kejing; Wen, Jinsheng; Zhang, Changjin; Yang, Huan; Zhang, Yuheng; Wen, Hai-Hu

    2017-01-01

    Topological superconductors are a very interesting and frontier topic in condensed matter physics. Despite the tremendous efforts in exploring topological superconductivity, its presence is however still under heavy debate. The Dirac electrons have been proven to exist on the surface of a topological insulator. It remains unclear whether and how the Dirac electrons fall into Cooper pairing in an intrinsic superconductor with the topological surface states. Here we show the systematic study of scanning tunnelling microscope/spectroscopy on the possible topological superconductor SrxBi2Se3. We first demonstrate that only the intercalated Sr atoms can induce superconductivity. Then we show the full superconducting gaps without any in-gap density of states as expected theoretically for a bulk topological superconductor. Finally, we find that the surface Dirac electrons will simultaneously condense into the superconducting state within the superconducting gap. This vividly demonstrates how the surface Dirac electrons are driven into Cooper pairs. PMID:28198378

  16. Excitons and Cooper pairs two composite bosons in many-body physics

    CERN Document Server

    Combescot, Monique

    2015-01-01

    This book bridges a gap between two major communities of Condensed Matter Physics, Semiconductors and Superconductors, that have thrived independently. Through an original perspective that their key particles, excitons and Cooper pairs, are composite bosons, the authors raise fundamental questions of current interest: how does the Pauli exclusion principle wield its power on the fermionic components of bosonic particles at a microscopic level and how this affects the macroscopic physics? What can we learn from Wannier and Frenkel excitons and from Cooper pairs that helps us understand "bosonic condensation" of composite bosons and its difference from Bose-Einstein condensation of elementary bosons? The authors start from solid mathematical and physical foundation to derive excitons and Cooper pairs. They further introduce Shiva diagrams as a graphic support to grasp the many-body physics induced by fermion exchange - a novel mechanism not visualized by standard Feynman diagrams. Advanced undergraduate or grad...

  17. Double quantum dot Cooper-pair splitter at finite couplings

    Science.gov (United States)

    Hussein, Robert; Jaurigue, Lina; Governale, Michele; Braggio, Alessandro

    2016-12-01

    We consider the subgap physics of a hybrid double-quantum dot Cooper-pair splitter with large single-level spacings, in the presence of tunneling between the dots and finite Coulomb intra- and interdot Coulomb repulsion. In the limit of a large superconducting gap, we treat the coupling of the dots to the superconductor exactly. We employ a generalized master-equation method, which easily yields currents, noise, and cross-correlators. In particular, for finite inter- and intradot Coulomb interaction, we investigate how the transport properties are determined by the interplay between local and nonlocal tunneling processes between the superconductor and the dots. We examine the effect of interdot tunneling on the particle-hole symmetry of the currents with and without spin-orbit interaction. We show that spin-orbit interaction in combination with finite Coulomb energy opens the possibility to control the nonlocal entanglement and its symmetry (singlet/triplet). We demonstrate that the generation of nonlocal entanglement can be achieved even without any direct nonlocal coupling to the superconducting lead.

  18. Thermoelectric-induced unitary Cooper pair splitting efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Zhan; Fang, Tie-Feng [Center for Interdisciplinary Studies and Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Li, Lin [Department of Physics, Southern University of Science and Technology of China, Shenzhen 518005 (China); Luo, Hong-Gang [Center for Interdisciplinary Studies and Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Beijing Computational Science Research Center, Beijing 100084 (China)

    2015-11-23

    Thermoelectric effect is exploited to optimize the Cooper pair splitting efficiency in a Y-shaped junction, which consists of two normal leads coupled to an s-wave superconductor via double noninteracting quantum dots. Here, utilizing temperature difference rather than bias voltage between the two normal leads, and tuning the two dot levels such that the transmittance of elastic cotunneling process is particle-hole symmetric, we find current flowing through the normal leads are totally contributed from the splitting of Cooper pairs emitted from the superconductor. Such a unitary splitting efficiency is significantly better than the efficiencies obtained in experiments so far.

  19. Behaviour of entanglement and Cooper pairs under relativistic boosts

    CERN Document Server

    Palge, Veiko; Dunningham, Jacob A

    2011-01-01

    Recent work has shown how single-particle entangled states are transformed when boosted in relativistic frames for certain restricted geometries. Here we extend that work to consider completely general inertial boosts. We then apply our single particle results to multiparticle entanglements by focussing on Cooper pairs of electrons. We show that a standard Cooper pair state consisting of a spin-singlet acquires spin-triplet components in a relativistically boosted inertial frame, regardless of the geometry. We also show that, if we start with a spin-triplet pair, two out of the three triplet states acquire a singlet component, the size of which depends on the geometry. This transformation between the different singlet and triplet superconducting pairs may lead to a better understanding of unconventional superconductivity.

  20. Behavior of entanglement and Cooper pairs under relativistic boosts

    Energy Technology Data Exchange (ETDEWEB)

    Palge, Veiko; Dunningham, Jacob A. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Vedral, Vlatko [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

    2011-10-15

    Recent work [J. A. Dunningham, V. Palge, and V. Vedral, Phys. Rev. A 80, 044302 (2009)] has shown how single-particle entangled states are transformed when boosted in relativistic frames for certain restricted geometries. Here we extend that work to consider completely general inertial boosts. We then apply our single-particle results to multiparticle entanglements by focusing on Cooper pairs of electrons. We show that a standard Cooper pair state consisting of a spin-singlet acquires spin-triplet components in a relativistically boosted inertial frame, regardless of the geometry. We also show that, if we start with a spin-triplet pair, two out of the three triplet states acquire a singlet component, the size of which depends on the geometry. This transformation between the different singlet and triplet superconducting pairs may lead to a better understanding of unconventional superconductivity.

  1. Extra-pair mating and evolution of cooperative neighbourhoods.

    Directory of Open Access Journals (Sweden)

    Sigrunn Eliassen

    Full Text Available A striking but unexplained pattern in biology is the promiscuous mating behaviour in socially monogamous species. Although females commonly solicit extra-pair copulations, the adaptive reason has remained elusive. We use evolutionary modelling of breeding ecology to show that females benefit because extra-pair paternity incentivizes males to shift focus from a single brood towards the entire neighbourhood, as they are likely to have offspring there. Male-male cooperation towards public goods and dear enemy effects of reduced territorial aggression evolve from selfish interests, and lead to safer and more productive neighbourhoods. The mechanism provides adaptive explanations for the common empirical observations that females engage in extra-pair copulations, that neighbours dominate as extra-pair sires, and that extra-pair mating correlates with predation mortality and breeding density. The models predict cooperative behaviours at breeding sites where males cooperate more towards public goods than females. Where maternity certainty makes females care for offspring at home, paternity uncertainty and a potential for offspring in several broods make males invest in communal benefits and public goods. The models further predict that benefits of extra-pair mating affect whole nests or neighbourhoods, and that cuckolding males are often cuckolded themselves. Derived from ecological mechanisms, these new perspectives point towards the evolution of sociality in birds, with relevance also for mammals and primates including humans.

  2. Extra-pair mating and evolution of cooperative neighbourhoods.

    Science.gov (United States)

    Eliassen, Sigrunn; Jørgensen, Christian

    2014-01-01

    A striking but unexplained pattern in biology is the promiscuous mating behaviour in socially monogamous species. Although females commonly solicit extra-pair copulations, the adaptive reason has remained elusive. We use evolutionary modelling of breeding ecology to show that females benefit because extra-pair paternity incentivizes males to shift focus from a single brood towards the entire neighbourhood, as they are likely to have offspring there. Male-male cooperation towards public goods and dear enemy effects of reduced territorial aggression evolve from selfish interests, and lead to safer and more productive neighbourhoods. The mechanism provides adaptive explanations for the common empirical observations that females engage in extra-pair copulations, that neighbours dominate as extra-pair sires, and that extra-pair mating correlates with predation mortality and breeding density. The models predict cooperative behaviours at breeding sites where males cooperate more towards public goods than females. Where maternity certainty makes females care for offspring at home, paternity uncertainty and a potential for offspring in several broods make males invest in communal benefits and public goods. The models further predict that benefits of extra-pair mating affect whole nests or neighbourhoods, and that cuckolding males are often cuckolded themselves. Derived from ecological mechanisms, these new perspectives point towards the evolution of sociality in birds, with relevance also for mammals and primates including humans.

  3. Paired twins and [112] morphology in GaP nanowires.

    Science.gov (United States)

    Algra, Rienk E; Verheijen, Marcel A; Feiner, Lou-Fé; Immink, George G W; Theissmann, Ralf; van Enckevort, Willem J P; Vlieg, Elias; Bakkers, Erik P A M

    2010-07-14

    Formation of random as well as periodic planar defects can occur during vapor-liquid-solid growth of nanowires with the zinc-blende crystal structure. Here we investigate the formation of pairs of twin planes in GaP nanowires. In such pairs, the first twin plane is formed at a random position, rapidly followed by the formation of a second twin plane of which the position is directly related to that of the first one. We show that the triangular [112] morphology of the nanowire is a key element in the formation of these twin pairs. We have extended our previous kinetic nucleation model and show that this describes the development of the nanowire morphology and its relation with the formation of single and paired twin planes.

  4. Weak nuclear collectivity from proton and neutron pairing gaps

    CERN Document Server

    Orce, Nico

    2010-01-01

    I explore weakly-collective singly-closed shell nuclei with high-j shells where active valence neutrons and particle-particle correlations may be the dominant collective degree of freedom. The combination of large and close-lying proton and neutron pairing gaps extracted from experimental masses seems to charaterize the origin of the weak collectivity observed in Ni and Sn superfluids with $N\\approx Z$. The trend of $E2$ transition strengths, i.e., $B(E2; 2^+_1\\rightarrow 0^+_1)$ values, in these nuclei is predicted from proton and neutron pairing-gap information. The agreement with the Ni isotopes is excellent and recent experimental results support the trend in the Sn isotopes. This work emphasizes the importance of atomic masses in elucidating nuclear-structure properties. In particular, it indicates that many-body microscopic properties such as nuclear collectivity could be directly inferred from more macroscopic average properties such as atomic masses.

  5. Dynamical Cooper pairing in nonequilibrium electron-phonon systems

    Science.gov (United States)

    Knap, Michael; Babadi, Mehrtash; Refael, Gil; Martin, Ivar; Demler, Eugene

    2016-12-01

    We analyze Cooper pairing instabilities in strongly driven electron-phonon systems. The light-induced nonequilibrium state of phonons results in a simultaneous increase of the superconducting coupling constant and the electron scattering. We demonstrate that the competition between these effects leads to an enhanced superconducting transition temperature in a broad range of parameters. Our results may explain the observed transient enhancement of superconductivity in several classes of materials upon irradiation with high intensity pulses of terahertz light, and may pave new ways for engineering high-temperature light-induced superconducting states.

  6. Studying temperature dependence of pairing gap parameter in a nucleus as a small superconducting system

    Science.gov (United States)

    Rahmatinejad, A.; Razavi, R.; Kakavand, T.

    2016-07-01

    In this paper, we have taken the effect of small size of nucleus and static fluctuations into account in the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity calculations of 45Ti nucleus. Thermodynamic quantities of 45Ti have been extracted within the BCS model with the inclusion of the average value of the pairing gap square, extracted by the modified Ginzburg-Landau (MGL) method for small systems. Calculated values of the excitation energy and entropy within the MGL+BCS method improve the extracted results within the usual BCS model and show a smooth behavior around the critical temperature with a very good agreement with the semi-empirical values. The result of using MGL+BCS method for the heat capacity of 45Ti is compared with the corresponding semi-empirical values and the calculated values within the BCS, static path approximation (SPA) and Modified Pairing gap BCS (MPBCS) which is a method that was proposed in our previous publications. Both MGL+BCS and MPBCS avoid the discontinuity of the heat capacity curve, which is observed in the usual BCS method, and lead to an S-shaped curve with a good agreement with the semi-empirical results.

  7. Time-resolved measurements of Cooper-pair radiative recombination in InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Mou, S. S.; Nakajima, H.; Kumano, H.; Suemune, I., E-mail: isuemune@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020 (Japan); Irie, H. [NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198 (Japan); Asano, Y. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Akahane, K.; Sasaki, M. [National Institute of Information and Communication Technology, Koganei 184-8795 (Japan); Murayama, A. [Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814 (Japan)

    2015-08-21

    We studied InAs quantum dots (QDs) where electron Cooper pairs penetrate from an adjacent niobium (Nb) superconductor with the proximity effect. With time-resolved luminescence measurements at the wavelength around 1550 nm, we observed luminescence enhancement and reduction of luminescence decay time constants at temperature below the superconducting critical temperature (T{sub C}) of Nb. On the basis of these measurements, we propose a method to determine the contribution of Cooper-pair recombination in InAs QDs. We show that the luminescence enhancement measured below T{sub C} is well explained with our theory including Cooper-pair recombination.

  8. Generic strong coupling behavior of Cooper pairs in the surface of superfluid nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pillet, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France); Sandulescu, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France)]|[Institute of Physics and Nuclear Engineering, 76900 Bucharest (Romania)]|[Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France); Schuck, P. [Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France)]|[Universite Paris-Sud, Orsay, F-91505 (France)

    2007-01-15

    With realistic HFB calculations, using the D1S Gogny force, we reveal a generic behavior of concentration of small sized Cooper pairs (2-3 fm) in the surface of superfluid nuclei. This study confirms and extends previous results given in the literature that use more schematic approaches. It is shown that the strong concentration of pair probability of small Cooper pairs in the nuclear surface is a quite general and generic feature and that nuclear pairing is much closer to the strong coupling regime than previously assumed.

  9. Universal quantum gates for Single Cooper Pair Box based quantum computing

    Science.gov (United States)

    Echternach, P.; Williams, C. P.; Dultz, S. C.; Braunstein, S.; Dowling, J. P.

    2000-01-01

    We describe a method for achieving arbitrary 1-qubit gates and controlled-NOT gates within the context of the Single Cooper Pair Box (SCB) approach to quantum computing. Such gates are sufficient to support universal quantum computation.

  10. Pairing of Pre-Service and Cooperating Teachers during Student Internship: Opinions of Collaborative Relationships

    Science.gov (United States)

    Lawley, Jennifer Avery

    2012-01-01

    This study investigated the opinions of collaborative relationships of pre-service and cooperating teachers during the internship semester. The primary purpose of the study was to determine if purposefully pairing pre-service and cooperating teachers with similar personality traits improved the opinions of collaboration. Using the method of…

  11. On magnon mediated Cooper pair formation in ferromagnetic superconductors

    Directory of Open Access Journals (Sweden)

    Rakesh Kar

    2014-08-01

    Full Text Available Identification of pairing mechanism leading to ferromagnetic superconductivity is one of the most challenging issues in condensed matter physics. Although different models have been proposed to explain this phenomenon, a quantitative understanding about this pairing is yet to be achieved. Using the localized-itinerant model, we find that in ferromagnetic superconducting materials both triplet pairing and singlet pairing of electrons are possible through magnon exchange depending upon whether the Debye cut off frequency of magnons is greater or lesser than the Hund's coupling (J multiplied by average spin (S per site. Taking into account the repulsive interaction due to the existence of paramagnons, we also find an expression for effective interaction potential between a pair of electrons with opposite spins. We apply the developed formalism in case of UGe2 and URhGe. The condition of singlet pairing is found to be fulfilled in these cases, as was previously envisaged by Suhl [Suhl, Phys. Rev. Lett. 87, 167007 (2001]. We compute the critical temperatures of URhGe at ambient pressure and of UGe2 under different pressures for the first time through BCS equation. Thus, this work outlines a very simple way to evaluate critical temperature in case of a superconducting system. A close match with the available experimental results strongly supports our theoretical treatment.

  12. Negative refractive index of metallic cross-I-shaped pairs: origin and evolution with pair gap width.

    Science.gov (United States)

    Ma, Y G; Wang, X C; Ong, C K

    2008-07-01

    A structured composite of the negative index of refraction was fabricated by one layer of cross-I-shaped metal pairs. In this structure, the electric and magnetic inclusions were effectively integrated into one small unit. We varied the spacing of the cross pair to control the location of the magnetic resonance mode and their intercoupling with the electric mode. The frequency dependences of permittivity, permeability, and refractive indices with different gap widths of the pairs were systematically discussed by free-space measurement as well as numerical simulation. A spacing window dependent on the geometrical parameters was found in which the real part of the refractive index could have a negative value. The one-layer cross-pair pattern proposed in this work can be extended to three-dimensional structures with well-controlled interlayer coupling that will greatly facilitate the fabrication and measurement of negative-index materials in high frequencies.

  13. Ion Pairs or Neutral Molecule Adducts? Cooperativity in Hydrogen Bonding

    Science.gov (United States)

    DeKock, Roger L.; Schipper, Laura A.; Dykhouse, Stephanie C.; Heeringa, Lee P.; Brandsen, Benjamin M.

    2009-01-01

    We performed theoretical studies on the systems NH[subscript 3] times HF times mH[subscript 2]O, NH[subscript 3] times HCl times mH[subscript 2]O, with m = 0, 1, 2, and 6. The molecules with m = 0 form hydrogen-bonded adducts with little tendency to form an ion-pair structure. The molecule NH[subscript 3] times HCl times H[subscript 2]O cannot be…

  14. Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors.

    Science.gov (United States)

    Wang, Qisi; Park, J T; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J W; Ivanov, A; Chi, Songxue; Matsuda, M; Cao, Huibo; Birgeneau, R J; Efremov, D V; Zhao, Jun

    2016-05-13

    An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s-wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s_{±} or d-wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in T_{c} in the S-doped iron selenide superconductors K_{x}Fe_{2-y}(Se_{1-z}S_{z})_{2}. We show that a rather sharp magnetic resonant mode well below the superconducting gap (2Δ) in the undoped sample (z=0) is replaced by a broad hump structure above 2Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

  15. Pseudogap from preformed Cooper pairs in a platinum-iron-arsenide superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Surmach, M.A.; Brueckner, F.; Kamusella, S.; Sarkar, R.; Portnichenko, P.Y.; Klauss, H.H.; Inosov, D.S. [TU Dresden (Germany); Park, J.T. [MLZ, Garching (Germany); Luetkens, H.; Biswas, P. [PSI, Villigen (Switzerland); Choi, W.J.; Seo, Y.I.; Kwon, Y.S. [DGIST, Daegu (Korea, Republic of)

    2015-07-01

    Using a combination of μSR, INS and NMR, we investigated the novel iron-based superconductor with a triclinic crystal structure (CaFe{sub 1-x}Pt{sub x}As){sub 10}Pt{sub 3}As{sub 8} (T{sub c}=13 K). The T-dependence of the superfluid density from our μSR relaxation-rate measurements indicates the presence of two superconducting gaps. According to our INS measurements, commensurate spin fluctuations are centered at the (π, 0) wave vector. Their intensity is unchanged across T{sub c}, indicating the absence of a spin resonance typical for many Fe-based superconductors. Instead, we observed a peak in the spin-excitation spectrum around ℎω{sub 0}=7 meV at the same wave vector, which persists above T{sub c}. The temperature dependence of magnetic intensity at 7 meV revealed an anomaly around T*=45 K related to the disappearance of this new mode. A suppression of the spin-lattice relaxation rate, 1/T{sub 1}T, observed by NMR immediately below T* without any notable subsequent anomaly at T{sub c}, indicates that T* could mark the onset of a pseudogap in (CaFe{sub 1-x}Pt{sub x}As){sub 10}Pt{sub 3}As{sub 8}, which is likely associated with the emergence of preformed Cooper pairs.

  16. Effects of Ion Beam Irradiation on Nanoscale InOx Cooper-Pair Insulators

    Directory of Open Access Journals (Sweden)

    Srdjan Milosavljević

    2013-01-01

    Full Text Available This paper examines the effects of irradiating indium oxide films of nanoscale thickness by ion beams, when these films are in the Cooper-pair insulator state. Radiation effects are predicted on the basis of Monte Carlo simulations of ion transport. Results of numerical experiments are interpreted within the theoretical model of a Cooper-pair insulator. The study suggests that radiation-induced changes in InOx films exposed to ion beams could significantly alter their current-voltage characteristics and that a transition to a metallic state is possible, due to radiation-induced perturbation of the fine-tuned granular structure. Furthermore, incident and displaced ions can break up enough Cooper pairs in InOx films to cause dissolution of this specific insulating state.

  17. Controlling Statistical Properties of a Cooper Pair Box Interacting with a Nanomechanical Resonator

    CERN Document Server

    Valverde, C; Baseia, a B

    2011-01-01

    We investigate the quantum entropy, its power spectrum, and the excitation inversion of a Cooper pair box interacting with a nanomechanical resonator, the first initially prepared in its excited state, the second prepared in a "cat"-state. The method uses the Jaynes-Cummings model with damping, with different decay rates of the Cooper pair box and distinct detuning conditions, including time dependent detunings. Concerning the entropy, it is found that the time dependent detuning turns the entanglement more stable in comparison with previous results in literature. With respect to the Cooper pair box excitation inversion, while the presence of detuning destroys the its collapses and revivals, it is shown that with a convenient time dependent detuning one recovers such events in a nice way.

  18. Radiation hardness of indium oxide films in the Cooper-pair insulator state

    Directory of Open Access Journals (Sweden)

    Lazarević Đorđe R.

    2012-01-01

    Full Text Available This paper investigates possible radiation effects in the Cooper-pair insulator state of indium oxide films. Radiation effects are predicted on the basis of Monte Carlo simulations. Results of a combined theoretical and numerical analysis suggest that radiation-induced changes in the investigated films could significantly affect their current-voltage characteristics, and that a transition to a metallic state is possible, due to radiation-induced disruption of the fine-tuned granular structure. Dissociation of Cooper pairs, caused by both the incident radiation and the ions displaced within InOx films, can also destroy the conditions for this specific insulating state to subsist.

  19. Visualised predictions of gap anisotropy to test new electron pairing scheme

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, X.H.; Walmsley, D.G., E-mail: dg.walmsley@qub.ac.uk

    2017-03-15

    Highlights: • Proposed test of new electron pairing scheme. • Energy gap anisotropy maps. • Reinterpretation of experimental data on gap anisotropy. • Critical comparison of theoretical results with sparse experimental data in lead, aluminium, niobium and tantalum. • Identification of absence of significant (>1%) gap anisotropy in single crystal tunnelling data. - Abstract: The rich and fertile but not yet adequately exploited ground of superconductor anisotropy is proposed as a test bed for a new empirical scheme of electron pairing. The scheme is directed to resolving a numerical and conceptual difficulty in the BCS theory. The original theoretical formulation of the anisotropy problem by Bennett is adopted and its outcomes extensively explored. Here the Bennett conclusion that in metallic superconductors phonon anisotropy is the principal source of gap anisotropy is accepted. Values of the energy gap are visualised globally in k-space with unprecedented detail and accuracy. Comparison is made between the anisotropy pattern from the new and the usual BCS pairing schemes. Differences are revealed for future experimental resolution.

  20. Fast local fragment chaining using sum-of-pair gap costs

    DEFF Research Database (Denmark)

    Otto, Christian; Hoffmann, Steve; Gorodkin, Jan

    2011-01-01

    , and rank the fragments to improve the specificity. Results: Here we present a fast and flexible fragment chainer that for the first time also supports a sum-of-pair gap cost model. This model has proven to achieve a higher accuracy and sensitivity in its own field of application. Due to a highly time......-efficient index structure our method outperforms the only existing tool for fragment chaining under the linear gap cost model. It can easily be applied to the output generated by alignment tools such as segemehl or BLAST. As an example we consider homology-based searches for human and mouse snoRNAs demonstrating...... that a highly sensitive BLAST search with subsequent chaining is an attractive option. The sum-of pair gap costs provide a substantial advantage is this context. Conclusions: Chaining of short match fragments helps to quickly and accurately identify regions of homology that may not be found using local...

  1. High frequency of extra-pair paternity in an urban population of Cooper's Hawks

    Science.gov (United States)

    Rosenfield, Robert N.; Sonsthagen, Sarah A.; Stout, William C.; Talbot, Sandra

    2015-01-01

    Raptors exhibit some of the highest rates of intra-pair copulations among birds, perhaps in an attempt by males to reduce the risk of being cuckolded. Indeed, the frequency of extra-pair fertilizations reported in studies of raptors to date is relatively low (0-11.2%). Socially monogamous Cooper's Hawks (Accipiter cooperii) exhibit one of the highest copulation rates among birds, yet there are no published accounts of extra-pair copulations (or paternity). We studied a population of Cooper's Hawks in Milwaukee, Wisconsin, during three breeding seasons (2003, 2004, and 2007), examining the possible effects of age (1 yr old vs. ≥ 2 yr old), adult mass, and brood size on the frequency of extra-pair paternity (EPP). We found that 19.3% of nestlings (N = 27/140) were extra-pair young (EPY), and 34% of all broods (N = 15/44) had at least one EPY. The sires of the EPY in our study were identified for only two broods, suggesting that floater males may have engaged in extra-pair copulations with territorial females. We found that brood size was a good predictor of the occurrence of EPP (EPP) in nests, but adult mass and female age were not. To our knowledge, these possible correlates of the occurrence of EPP in raptors had not previously been investigated. Male Cooper's Hawks provide food for females during the pre-nesting period, and delivery of food is, in contrast to other raptor species, typically followed by copulation. Thus, one possible explanation of the relatively high rates of EPP in our study is that females might accept or even solicit extra-pair copulations from males other than their mates as a means of maximizing energy intake for egg production. Such behavior might be particularly likely in our study area, i.e., a food-rich urban setting with a high breeding density of Cooper's Hawks.

  2. The Effect of Incorporating Cooperative Learning Principles in Pair Programming for Student Teachers

    Science.gov (United States)

    Mentz, E.; van der Walt, J. L.; Goosen, L.

    2008-01-01

    Based on their quantitative and qualitative investigations, the authors conclude that pair programming as a strategy for teaching student teachers could be made more effective through the incorporation of principles associated with cooperative learning. They substantiate this claim by referring to a literature study about the advantages and…

  3. Spontaneous pairing and cooperative movements of micro-particles in a two dimensional plasma crystal

    Energy Technology Data Exchange (ETDEWEB)

    Zhdanov, S. K. [Max Planck Institute for extraterrestrial Physics, D-85741 Garching (Germany); Couëdel, L., E-mail: lenaic.couedel@univ-amu.fr [CNRS, Université d' Aix-Marseille, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Nosenko, V.; Thomas, H. M. [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum fur Luft-und-Raumfahrt, Oberpfaffenhofen (Germany); Morfill, G. E. [Max Planck Institute for extraterrestrial Physics, D-85741 Garching (Germany); BMSTU Centre for Plasma Science and Technology, Moscow (Russian Federation)

    2015-05-15

    In an argon plasma of 20 W rf discharge at a pressure of 1.38 Pa, a stable highly ordered monolayer of microparticles is suspended. We observe spontaneous particle pairing when suddenly reducing the gas pressure. Special types of dynamical activity, in particular, entanglement and cooperative movements of coupled particles have been registered. In the course of the experiment first appeared single vertical pairs of particles, in further they gradually accumulated causing melting of the entire crystal. To record pairing events, the particle suspension is side-view imaged using a vertically extended laser sheet. The long-lasting pre-melting phase assured the credible recording and identification of isolated particle pairs. The high monolayer charge density is crucial to explain the spontaneous pairing events observed in our experiments as the mutual repulsion between the particles comprising the monolayer make its vertical extend thicker.

  4. Cooper pairing in the insulating valence band in iron-based superconductors

    Science.gov (United States)

    Hu, Lun-Hui; Chen, Wei-Qiang; Zhang, Fu-Chun

    2015-04-01

    Conventional Cooper pairing arises from attractive interaction of electrons in the metallic bands. A recent experiment on Co-doped LiFeAs shows superconductivity in the insulating valence band, which is evolved from a metallic hole band upon doping. Here we examine this phenomenon by studying superconductivity in a three-orbital Hamiltonian relevant to the doped LiFeAs. We show explicitly that Cooper pairing of the insulating hole band requires a finite pairing interaction strength. For strong coupling, the superconductivity in the hole band is robust against the sink of the hole band below the Fermi level. Our theory predicts a substantial upward shift of the chemical potential in the superconducting transition for Co-doped LiFeAs.

  5. Bound states and Cooper pairs of molecules in 2D optical lattices bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Guardian, A.; Dominguez-Castro, G.A.; Paredes, R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico)

    2016-08-15

    We investigate the formation of Cooper pairs, bound dimers and the dimer-dimer elastic scattering of ultracold dipolar Fermi molecules confined in a 2D optical lattice bilayer configuration. While the energy and their associated bound states are determined in a variational way, the correlated two-molecule pair is addressed as in the original Cooper formulation. We demonstrate that the 2D lattice confinement favors the formation of zero center mass momentum bound states. Regarding the Cooper pairs binding energy, this depends on the molecule populations in each layer. Maximum binding energies occur for non-zero (zero) pair momentum when the Fermi system is polarized (unpolarized). We find an analytic expression for the dimer-dimer effective interaction in the deep BEC regime. The present analysis represents a route for addressing the BCS-BEC crossover in dipolar Fermi gases confined in 2D optical lattices within the current experimental panorama. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Unconventional symmetries of Fermi liquid and Cooper pairing properties with electric and magnetic dipolar fermions.

    Science.gov (United States)

    Li, Yi; Wu, Congjun

    2014-12-10

    The rapid experimental progress of ultra-cold dipolar fermions opens up a whole new opportunity to investigate novel many-body physics of fermions. In this article, we review theoretical studies of the Fermi liquid theory and Cooper pairing instabilities of both electric and magnetic dipolar fermionic systems from the perspective of unconventional symmetries. When the electric dipole moments are aligned by the external electric field, their interactions exhibit the explicit d(r(2)-3z(2)) anisotropy. The Fermi liquid properties, including the single-particle spectra, thermodynamic susceptibilities and collective excitations, are all affected by this anisotropy. The electric dipolar interaction provides a mechanism for the unconventional spin triplet Cooper pairing, which is different from the usual spin-fluctuation mechanism in solids and the superfluid (3)He. Furthermore, the competition between pairing instabilities in the singlet and triplet channels gives rise to a novel time-reversal symmetry breaking superfluid state. Unlike electric dipole moments which are induced by electric fields and unquantized, magnetic dipole moments are intrinsic proportional to the hyperfine-spin operators with a Lande factor. Its effects even manifest in unpolarized systems exhibiting an isotropic but spin-orbit coupled nature. The resultant spin-orbit coupled Fermi liquid theory supports a collective sound mode exhibiting a topologically non-trivial spin distribution over the Fermi surface. It also leads to a novel p-wave spin triplet Cooper pairing state whose spin and orbital angular momentum are entangled to the total angular momentum J = 1 dubbed the J-triplet pairing. This J-triplet pairing phase is different from both the spin-orbit coupled (3)He-B phase with J = 0 and the spin-orbit decoupled (3)He-A phase.

  7. Superconductivity on a quasiperiodic lattice: Extended-to-localized crossover of Cooper pairs

    Science.gov (United States)

    Sakai, Shiro; Takemori, Nayuta; Koga, Akihisa; Arita, Ryotaro

    2017-01-01

    We study a possible superconductivity in quasiperiodic systems by portraying the issue within the attractive Hubbard model on a Penrose lattice. Applying a real-space dynamical mean-field theory to the model consisting of 4181 sites, we find a superconducting phase at low temperatures. Reflecting the nonperiodicity of the Penrose lattice, the superconducting state exhibits an inhomogeneity. According to the type of the inhomogeneity, the superconducting phase is categorized into three different regions which cross over each other. Among them, the weak-coupling region exhibits spatially extended Cooper pairs, which are nevertheless distinct from the conventional pairing of two electrons with opposite momenta.

  8. Nonequilibrium Second-Order Phase Transition in a Cooper-Pair Insulator.

    Science.gov (United States)

    Doron, A; Tamir, I; Mitra, S; Zeltzer, G; Ovadia, M; Shahar, D

    2016-02-05

    In certain disordered superconductors, upon increasing the magnetic field, superconductivity terminates with a direct transition into an insulating phase. This phase is comprised of localized Cooper pairs and is termed a Cooper-pair insulator. The current-voltage characteristics measured in this insulating phase are highly nonlinear and, at low temperatures, exhibit abrupt current jumps. Increasing the temperature diminishes the jumps until the current-voltage characteristics become continuous. We show that a direct correspondence exists between our system and systems that undergo an equilibrium, second-order, phase transition. We illustrate this correspondence by comparing our results to the van der Waals equation of state for the liquid-gas mixture. We use the similarities to identify a critical point where an out of equilibrium second-order-like phase transition occurs in our system. Approaching the critical point, we find a power-law behavior with critical exponents that characterizes the transition.

  9. Stimulated emission of Cooper pairs in a high-temperature cuprate superconductor

    Science.gov (United States)

    Zhang, Wentao; Miller, Tristan; Smallwood, Christopher L.; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Kaindl, R. A.; Lee, Dung-Hai; Lanzara, Alessandra

    2016-07-01

    The concept of stimulated emission of bosons has played an important role in modern science and technology, and constitutes the working principle for lasers. In a stimulated emission process, an incoming photon enhances the probability that an excited atomic state will transition to a lower energy state and generate a second photon of the same energy. It is expected, but not experimentally shown, that stimulated emission contributes significantly to the zero resistance current in a superconductor by enhancing the probability that scattered Cooper pairs will return to the macroscopically occupied condensate instead of entering any other state. Here, we use time- and angle-resolved photoemission spectroscopy to study the initial rise of the non-equilibrium quasiparticle population in a Bi2Sr2CaCu2O8+δ cuprate superconductor induced by an ultrashort laser pulse. Our finding reveals significantly slower buildup of quasiparticles in the superconducting state than in the normal state. The slower buildup only occurs when the pump pulse is too weak to deplete the superconducting condensate, and for cuts inside the Fermi arc region. We propose this is a manifestation of stimulated recombination of broken Cooper pairs, and signals an important momentum space dichotomy in the formation of Cooper pairs inside and outside the Fermi arc region.

  10. Stimulated emission of Cooper pairs in a high-temperature cuprate superconductor.

    Science.gov (United States)

    Zhang, Wentao; Miller, Tristan; Smallwood, Christopher L; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Kaindl, R A; Lee, Dung-Hai; Lanzara, Alessandra

    2016-01-01

    The concept of stimulated emission of bosons has played an important role in modern science and technology, and constitutes the working principle for lasers. In a stimulated emission process, an incoming photon enhances the probability that an excited atomic state will transition to a lower energy state and generate a second photon of the same energy. It is expected, but not experimentally shown, that stimulated emission contributes significantly to the zero resistance current in a superconductor by enhancing the probability that scattered Cooper pairs will return to the macroscopically occupied condensate instead of entering any other state. Here, we use time- and angle-resolved photoemission spectroscopy to study the initial rise of the non-equilibrium quasiparticle population in a Bi2Sr2CaCu2O8+δ cuprate superconductor induced by an ultrashort laser pulse. Our finding reveals significantly slower buildup of quasiparticles in the superconducting state than in the normal state. The slower buildup only occurs when the pump pulse is too weak to deplete the superconducting condensate, and for cuts inside the Fermi arc region. We propose this is a manifestation of stimulated recombination of broken Cooper pairs, and signals an important momentum space dichotomy in the formation of Cooper pairs inside and outside the Fermi arc region.

  11. Fast local fragment chaining using sum-of-pair gap costs

    Directory of Open Access Journals (Sweden)

    Hoffmann Steve

    2011-03-01

    Full Text Available Abstract Background Fast seed-based alignment heuristics such as BLAST and BLAT have become indispensable tools in comparative genomics for all studies aiming at the evolutionary relations of proteins, genes, and non-coding RNAs. This is true in particular for the large mammalian genomes. The sensitivity and specificity of these tools, however, crucially depend on parameters such as seed sizes or maximum expectation values. In settings that require high sensitivity the amount of short local match fragments easily becomes intractable. Then, fragment chaining is a powerful leverage to quickly connect, score, and rank the fragments to improve the specificity. Results Here we present a fast and flexible fragment chainer that for the first time also supports a sum-of-pair gap cost model. This model has proven to achieve a higher accuracy and sensitivity in its own field of application. Due to a highly time-efficient index structure our method outperforms the only existing tool for fragment chaining under the linear gap cost model. It can easily be applied to the output generated by alignment tools such as segemehl or BLAST. As an example we consider homology-based searches for human and mouse snoRNAs demonstrating that a highly sensitive BLAST search with subsequent chaining is an attractive option. The sum-of-pair gap costs provide a substantial advantage is this context. Conclusions Chaining of short match fragments helps to quickly and accurately identify regions of homology that may not be found using local alignment heuristics alone. By providing both the linear and the sum-of-pair gap cost model, a wider range of application can be covered. The software clasp is available at http://www.bioinf.uni-leipzig.de/Software/clasp/.

  12. Crossed Cooper Pair Transmission and Pure Spin Supercurrents through Strongly Spin-polarized Ferromagnets

    Science.gov (United States)

    Eschrig, Matthias

    2010-03-01

    Interfaces between solids with different ordering phenomena have become a focus of research in recent years. One reason is that new and unexpected phases that are not stable in either of the adjacent materials can appear in the interface regions. The mechanism for creating such phases is due to induced symmetry breaking, as opposed to spontaneous symmetry breaking in the bulk materials. As a prominent example I discuss interface-induced exotic superconductivity in heterostructures composed of conventional singlet superconductors and strongly spin-polarized ferromagnets. I present new intriguing effects, such as a tunable pure spin-supercurrent in a strongly spin-polarized ferromagnet contacted with only one superconducting electrode, and a difference in the critical currents for positive and negative bias in a high transmission ferromagnetic Josephson junction [1]. The latter, rather surprising effect has a physical explanation in terms of a new ``crossed Cooper pair transmission'' process. In this process two singlet Cooper pairs are coherently decomposed into two equal-spin triplet pairs, which are respectively transmitted via different spin bands in the ferromagnet, after which they again recombine into two singlet pairs. This effect is analogous to the well-known crossed Andreev reflection process, which however is strongly suppressed in this particular case. Furthermore, I discuss how the manipulation of interface spins can be used to pump triplet pairs. This opens an avenue for new types of superconducting quantum devices and new ways to test properties of exotic superconducting phases in experiment. [1] R. Grein, M. Eschrig, G. Metalidis, and G. Sch"on, Phys. Rev. Lett. 102, 227005 (2009).

  13. 77 FR 40085 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-American Gap...

    Science.gov (United States)

    2012-07-06

    ... safety, supervision, and general integrity of ``gap year'' educational programs. Patricia A. Brink... Gap Association Notice is hereby given that, on June 6, 2012, pursuant to Section 6(a) of the National Cooperative Research and Production Act of 1993, 15 U.S.C. 4301 et seq. (``the Act''), American Gap...

  14. Quantum Entropy of a Single Cooper-Pair Box Interacting with Two Electromagnetic Fields

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A Hamiltonian which represents the interaction between a single Cooper-pair box and two quantized electromagnetic fields is considered in order to find new ways for quantum information. The wave function in Schrdinger picture is obtained. The evolution of the entropy of the box as a function of the scaled time is ploted to measure the entanglement between the box and the fields. It is found that the entanglement is sensitive to the detuning between the Josephson energy and the fields frequency, increasing the detuning can decrease the entanglement.

  15. Relaxation time of the Cooper pairs near Tc in cuprate superconductors

    Science.gov (United States)

    Ramallo, M. V.; Carballeira, C.; Viña, J.; Veira, J. A.; Mishonov, T.; Pavuna, D.; Vidal, F.

    1999-10-01

    It is first shown that the thermal fluctuation effects on the transport and on the thermodynamic observables above the superconducting transition may provide, when they are analyzed simultaneously and consistently, a powerful tool to access the relaxation time, τ0, of the Cooper pairs with wave vector k = 0 in high-temperature cuprate superconductors (HTSC). Then, we apply this procedure to optimally doped YBa2Cu3O7 - δ (Y-123) crystals. It is found that in this HTSC τ0 follows, within 20% accuracy, the BCS temperature behaviour and amplitude given by τ0 = πhbar/[8kB(T - Tc0)].

  16. Spectroscopic Evidence of the Aharonov-Casher Effect in a Cooper Pair Box

    Science.gov (United States)

    Bell, M. T.; Zhang, W.; Ioffe, L. B.; Gershenson, M. E.

    2016-03-01

    We observe the effect of the Aharonov-Casher (AC) interference on the spectrum of a superconducting system containing a symmetric Cooper pair box (CPB) and a large inductance. By varying the charge ng induced on the CPB island, we observe oscillations of the device spectrum with the period Δ ng=2 e . These oscillations are attributed to the charge-controlled AC interference between the fluxon tunneling processes in the CPB Josephson junctions. The measured phase and charge dependences of the frequencies of the |0 ⟩→|1 ⟩ and |0 ⟩→|2 ⟩ transitions are in good agreement with our numerical simulations. Almost complete suppression of the single fluxon tunneling due to destructive interference is observed for the charge ng=e (2 n +1 ). The CPB in this regime enables fluxon pairing, which can be used for the development of parity-protected superconducting qubits.

  17. Cooper pair breaking and isotope effect coefficient variation in high-T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.P.; Pandey, R.K.; Singh, P. [G.B. Pant Univ. Pantanagar, Nainital (India)

    1996-06-01

    The effect of pair breaking on the isotope effect coefficient a = {minus}d ln T{sub c}/d ln M in La{sub 2{minus}x}Sr{sub x}CuO{sub 4} and Pr-, Ca-, and Zn-doped YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} and EuBa{sub 2}Cu{sub 3}O{sub 7{minus}x} is studied using the generalized Abrikosov-Gorkov theory recently employed by Singh and Kishore for superconductivity. It is argued that the isotope effect coefficient a can be further enhanced, in agreement with experimental observation, by considering the dependence of the characteristic scattering time {tau}{sub s} for Cooper pairs on the concentration n of impurities (both magnetic and nonmagnetic) and the disorder ignored by them.

  18. BCS-like critical fluctuations with limited overlap of Cooper pairs in FeSe

    Science.gov (United States)

    Yang, Huan; Chen, Guanyu; Zhu, Xiyu; Xing, Jie; Wen, Hai-Hu

    2017-08-01

    In conventional superconductors, very narrow superconducting-fluctuation regions are observed above Tc, because strong overlap of Cooper pairs occurs in a coherence volume 4 π ξ3/3 with ξ being the coherence length. In the bulk form of iron-chalcogenide superconductor FeSe, it is argued that the system may be located in the crossover region from Bardeen-Cooper-Schrieffer to Bose-Einstein condensation (BEC), where strong superconducting fluctuations are expected. In this respect, we carried out magnetization, specific heat, and Nernst effect measurements on FeSe single crystals in order to investigate the superconducting fluctuation effect near Tc. The temperature range of diamagnetization induced by superconducting fluctuations seems very narrow above Tc. The temperature-dependent magnetization curves measured at different magnetic fields do not cross at a single point. This is in sharp contrast to the situation in many cuprate superconductors, where such a crossing point has been taken as a clear signature of strong critical fluctuations. The magnetization data can be scaled according to the Ginzburg-Landau fluctuation theory for a quasi-two-dimensional system. However the scaling result cannot be described by the theoretical function of the fluctuation theory due to the limited fluctuation regions. The specific heat jump near Tc is rather sharp without the trace of strong superconducting fluctuations. This is also supported by the Nernst effect measurements which indicate a very narrow region for vortex motion above Tc. Associated with a very small value of Ginzburg number and further analyses, we conclude that the superconducting fluctuations are vanishingly weak above Tc in this material. Our results are strongly against the picture of significant phase fluctuations in FeSe single crystals, although the system has a very limited overlap of Cooper pairs in the coherence volume. This dichotomy provides new insights into the superconducting mechanism when the

  19. Signatures of nonlocal Cooper-pair transport and of a singlet-triplet transition in the critical current of a double-quantum-dot Josephson junction

    Science.gov (United States)

    Probst, B.; Domínguez, F.; Schroer, A.; Yeyati, A. Levy; Recher, P.

    2016-10-01

    We study the critical Josephson current flowing through a double quantum dot weakly coupled to two superconducting leads. We use analytical as well as numerical methods to investigate this setup in the limit of small and large bandwidth leads in all possible charging states, where we account for on-site interactions exactly. Our results provide clear signatures of nonlocal spin-entangled pairs, which support interpretations of recent experiments [R. S. Deacon, A. Oiwa, J. Sailer, S. Baba, Y. Kanai, K. Shibata, K. Hirakawa, and S. Tarucha, Nat. Commun. 6, 7446 (2015), 10.1038/ncomms8446]. In addition, we find that the ground state with one electron on each quantum dot can undergo a tunable singlet-triplet phase transition in the regime where the superconducting gap in the leads is not too large, which gives rise to an additional new signature of nonlocal Cooper-pair transport.

  20. Correlation-induced suppression of decoherence in capacitively coupled Cooper-pair boxes

    Science.gov (United States)

    Hu, Xuedong; You, J. Q.; Nori, Franco

    2005-03-01

    Charge fluctuations from gate bias and background traps severely limit the performance of a charge qubit in a Cooper-pair box (CPB). Here we discuss an encoding approachootnotetextJ.Q. You, X.Hu, and F. Nori, cond-mat/0407423. to control the decoherence effects of these charge fluctuations using two strongly capacitively coupled CPBs. This coupled-box system has a low-decoherence subspace of two states, for which we calculate the dephasing and relaxation rates using a master equation approach. Our results show that the inter-box Coulomb correlation can significantly suppress decoherence of this two-level system by reducing the strength of the system-environment interaction, making it a promising candidate as a logical qubit, encoded using two CPBs.

  1. Relaxation time of the Cooper pairs near T{sub c} in cuprate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ramallo, M.V.; Carballeira, C.; Vina, J.; Veira, J.A.; Mishonov, T.; Pavuna, D.; Vidal, F. [Santiago de Compostela Univ. (Spain). Lab. de Bajas Temperaturas y Superconductividad

    1999-10-01

    It is first shown that the thermal fluctuation effects on the transport and on the thermodynamic observables above the superconducting transition may provide, when they are analyzed simultaneously and consistently, a powerful tool to access the relaxation time, {tau}{sub 0}, of the Cooper pairs with wave vector k = 0 in high-temperature cuprate superconductors (HTSC). Then, we apply this procedure to optimally doped YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (Y-123) crystals. It is found that in this HTSC {tau}{sub 0} follows, within 20% accuracy, the BCS temperature behaviour and amplitude given by {tau}{sub 0} = {pi}{Dirac_h}[8k{sub B}(T-T{sub c0})]. (orig.)

  2. High-Efficiency Cooper-Pair Splitter in Quantum Anomalous Hall Insulator Proximity-Coupled with Superconductor.

    Science.gov (United States)

    Zhang, Ying-Tao; Deng, Xinzhou; Sun, Qing-Feng; Qiao, Zhenhua

    2015-01-01

    The quantum entanglement between two qubits is crucial for applications in the quantum communication. After the entanglement of photons was experimentally realized, much effort has been taken to exploit the entangled electrons in solid-state systems. Here, we propose a Cooper-pair splitter, which can generate spatially-separated but entangled electrons, in a quantum anomalous Hall insulator proximity-coupled with a superconductor. After coupling with a superconductor, the chiral edge states of the quantum anomalous Hall insulator can still survive, making the backscattering impossible. Thus, the local Andreev reflection becomes vanishing, while the crossed Andreev reflection becomes dominant in the scattering process. This indicates that our device can serve as an extremely high-efficiency Cooper-pair splitter. Furthermore, because of the chiral characteristic, our Cooper-pair splitter is robust against disorders and can work in a wide range of system parameters. Particularly, it can still function even if the system length exceeds the superconducting coherence length.

  3. PCTFPeval: a web tool for benchmarking newly developed algorithms for predicting cooperative transcription factor pairs in yeast.

    Science.gov (United States)

    Lai, Fu-Jou; Chang, Hong-Tsun; Wu, Wei-Sheng

    2015-01-01

    Computational identification of cooperative transcription factor (TF) pairs helps understand the combinatorial regulation of gene expression in eukaryotic cells. Many advanced algorithms have been proposed to predict cooperative TF pairs in yeast. However, it is still difficult to conduct a comprehensive and objective performance comparison of different algorithms because of lacking sufficient performance indices and adequate overall performance scores. To solve this problem, in our previous study (published in BMC Systems Biology 2014), we adopted/proposed eight performance indices and designed two overall performance scores to compare the performance of 14 existing algorithms for predicting cooperative TF pairs in yeast. Most importantly, our performance comparison framework can be applied to comprehensively and objectively evaluate the performance of a newly developed algorithm. However, to use our framework, researchers have to put a lot of effort to construct it first. To save researchers time and effort, here we develop a web tool to implement our performance comparison framework, featuring fast data processing, a comprehensive performance comparison and an easy-to-use web interface. The developed tool is called PCTFPeval (Predicted Cooperative TF Pair evaluator), written in PHP and Python programming languages. The friendly web interface allows users to input a list of predicted cooperative TF pairs from their algorithm and select (i) the compared algorithms among the 15 existing algorithms, (ii) the performance indices among the eight existing indices, and (iii) the overall performance scores from two possible choices. The comprehensive performance comparison results are then generated in tens of seconds and shown as both bar charts and tables. The original comparison results of each compared algorithm and each selected performance index can be downloaded as text files for further analyses. Allowing users to select eight existing performance indices and 15

  4. Cooperative activation of cardiac transcription through myocardin bridging of paired MEF2 sites

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Courtney M. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Hu, Jianxin [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Thomas, Reuben [Univ. of California, San Francisco, CA (United States). Gladstone Inst.; Gainous, T. Blair [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Celona, Barbara [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Sinha, Tanvi [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Dickel, Diane E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Genomics Division; Heidt, Analeah B. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Xu, Shan-Mei [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Bruneau, Benoit G. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Univ. of California, San Francisco, CA (United States). Gladstone Inst.; Pollard, Katherine S. [Univ. of California, San Francisco, CA (United States). Gladstone Inst.; Pennacchio, Len A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Genomics Division; Black, Brian L. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Univ. of California, San Francisco, CA (United States). Dept. of

    2017-03-28

    Enhancers frequently contain multiple binding sites for the same transcription factor. These homotypic binding sites often exhibit synergy, whereby the transcriptional output from two or more binding sites is greater than the sum of the contributions of the individual binding sites alone. Although this phenomenon is frequently observed, the mechanistic basis for homotypic binding site synergy is poorly understood. Here in this paper, we identify a bona fide cardiac-specific Prkaa2 enhancer that is synergistically activated by homotypic MEF2 binding sites. We show that two MEF2 sites in the enhancer function cooperatively due to bridging of the MEF2C-bound sites by the SAP domain-containing co-activator protein myocardin, and we show that paired sites buffer the enhancer from integration site-dependent effects on transcription in vivo. Paired MEF2 sites are prevalent in cardiac enhancers, suggesting that this might be a common mechanism underlying synergy in the control of cardiac gene expression in vivo.

  5. Direct Observation of NN Pairs Transfer in GaP1-xNx (x = 0.12%)

    Institute of Scientific and Technical Information of China (English)

    LU Yi-Jun; GAO Yu-Lin; ZHENG Jian-Sheng; ZHANG Yong; MASCARENHAS A.; XIN H.P.; TU C.W.

    2005-01-01

    @@ Time-resolved photoluminescence (TRPL) was applied to investigate the transient process in GaP1-xNx (x=0.12%) alloy. The filling, transferring and decay processes among nitrogen pairs are directly observed. The NN4pair, either not present or only a small obscure peak under a proper excitation condition in the steady-state photoluminescence spectrum, is well resolved by TRPL.

  6. Detection of a Cooper-pair density wave in Bi2Sr2CaCu2O8+x

    Science.gov (United States)

    Hamidian, M. H.; Edkins, S. D.; Joo, Sang Hyun; Kostin, A.; Eisaki, H.; Uchida, S.; Lawler, M. J.; Kim, E.-A.; MacKenzie, A. P.; Fujita, K.; Lee, Jinho; Davis, J. C. Séamus

    2016-04-01

    The quantum condensate of Cooper pairs forming a superconductor was originally conceived as being translationally invariant. In theory, however, pairs can exist with finite momentum Q, thus generating a state with a spatially modulated Cooper-pair density. Such a state has been created in ultracold 6Li gas but never observed directly in any superconductor. It is now widely hypothesized that the pseudogap phase of the copper oxide superconductors contains such a ‘pair density wave’ state. Here we report the use of nanometre-resolution scanned Josephson tunnelling microscopy to image Cooper pair tunnelling from a d-wave superconducting microscope tip to the condensate of the superconductor Bi2Sr2CaCu2O8+x. We demonstrate condensate visualization capabilities directly by using the Cooper-pair density variations surrounding zinc impurity atoms and at the Bi2Sr2CaCu2O8+x crystal supermodulation. Then, by using Fourier analysis of scanned Josephson tunnelling images, we discover the direct signature of a Cooper-pair density modulation at wavevectors QP ≈ (0.25, 0)2π/a0 and (0, 0.25)2π/a0 in Bi2Sr2CaCu2O8+x. The amplitude of these modulations is about five per cent of the background condensate density and their form factor exhibits primarily s or s‧ symmetry. This phenomenology is consistent with Ginzburg-Landau theory when a charge density wave with d-symmetry form factor and wavevector QC = QP coexists with a d-symmetry superconductor; it is also predicted by several contemporary microscopic theories for the pseudogap phase.

  7. How Cooper pairs vanish approaching the Mott insulator in Bi2Sr2CaCu2O8+delta.

    Science.gov (United States)

    Kohsaka, Y; Taylor, C; Wahl, P; Schmidt, A; Lee, Jhinhwan; Fujita, K; Alldredge, J W; McElroy, K; Lee, Jinho; Eisaki, H; Uchida, S; Lee, D-H; Davis, J C

    2008-08-28

    The antiferromagnetic ground state of copper oxide Mott insulators is achieved by localizing an electron at each copper atom in real space (r-space). Removing a small fraction of these electrons (hole doping) transforms this system into a superconducting fluid of delocalized Cooper pairs in momentum space (k-space). During this transformation, two distinctive classes of electronic excitations appear. At high energies, the mysterious 'pseudogap' excitations are found, whereas, at lower energies, Bogoliubov quasi-particles-the excitations resulting from the breaking of Cooper pairs-should exist. To explore this transformation, and to identify the two excitation types, we have imaged the electronic structure of Bi(2)Sr(2)CaCu(2)O(8+delta) in r-space and k-space simultaneously. We find that although the low-energy excitations are indeed Bogoliubov quasi-particles, they occupy only a restricted region of k-space that shrinks rapidly with diminishing hole density. Concomitantly, spectral weight is transferred to higher energy r-space states that lack the characteristics of excitations from delocalized Cooper pairs. Instead, these states break translational and rotational symmetries locally at the atomic scale in an energy-independent way. We demonstrate that these unusual r-space excitations are, in fact, the pseudogap states. Thus, as the Mott insulating state is approached by decreasing the hole density, the delocalized Cooper pairs vanish from k-space, to be replaced by locally translational- and rotational-symmetry-breaking pseudogap states in r-space.

  8. Dynamical charge and pseudospin currents in graphene and possible Cooper pair formation

    Science.gov (United States)

    Morawetz, K.

    2016-10-01

    Based on the quantum kinetic equations for systems with SU(2) structure, regularization-free density and pseudospin currents are calculated in graphene realized as the infinite-mass limit of electrons with quadratic dispersion and a proper spin-orbit coupling. Correspondingly the currents possess no quasiparticle part but only anomalous parts. The intraband and interband conductivities are discussed with respect to magnetic fields and magnetic domain puddles. It is found that the magnetic field and mean field of domains can be represented by an effective Zeeman field. For large Zeeman fields the dynamical conductivities become independent of the density and are universal in this sense. The different limits of vanishing density, relaxation, frequency, and Zeeman field are not interchangeable. The optical conductivity agrees well with the experimental values using screened impurity scattering and an effective Zeeman field. The universal value of Hall conductivity is shown to be modified due to the Zeeman field. The pseudospin current reveals an anomaly since a quasiparticle part appears though it vanishes for particle currents. The density and pseudospin response functions to an external electric field are calculated and the dielectric function is discussed with respect to collective excitations. A frequency and wave-vector range is identified where the dielectric function changes sign and the repulsive Coulomb potential becomes effectively attractive allowing Cooper pairing.

  9. The discipline gap and African Americans: defiance or cooperation in the high school classroom.

    Science.gov (United States)

    Gregory, Anne; Weinstein, Rhona S

    2008-08-01

    African Americans are over-represented in school suspensions, yet little is known about the underlying contributing dynamics. Study 1 reviewed a high school's annual discipline data and 442 students referred for defiance. African Americans were over-represented in referrals for defiance and most students received referrals from one or several teachers. This suggests that defiance referrals are specific to the classroom situation. Examining the situational specificity of referrals, Study 2 used repeated measures and multilevel modeling with a sub-sample of 30 African American students. Attendance, grades, and teacher reports showed that students behaved more defiantly and less cooperatively with teachers perceived as having untrustworthy authority. Predictors of African American student trust in teacher authority included teacher caring and high expectations, offering implications for lowering the discipline gap.

  10. Controlling the transmitted information of a multi-photon interacting with a single-Cooper pair box

    Energy Technology Data Exchange (ETDEWEB)

    Kadry, Heba, E-mail: hkadry1@yahoo.com; Abdel-Aty, Abdel-Haleem, E-mail: hkadry1@yahoo.com; Zakaria, Nordin, E-mail: hkadry1@yahoo.com [Computer and Information Science Department, Universiti Teknologi Petronas, Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Cheong, Lee Yen [Fundamental and Applied Science Department, Universiti Teknologi Petronas, Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-10-24

    We study a model of a multi-photon interaction of a single Cooper pair box with a cavity field. The exchange of the information using this system is studied. We quantify the fidelity of the transmitted information. The effect of the system parameters (detuning parameter, field photons, state density and mean photon number) in the fidelity of the transmitted information is investigated. We found that the fidelity of the transmitted information can be controlled using the system parameters.

  11. Quantum communication via controlled holes in the statistical distribution of excitations in a nanoresonator coupled to a Cooper pair box

    Institute of Scientific and Technical Information of China (English)

    C.Valverde; A.T.Avelar; B.Baseia

    2012-01-01

    We propose a scheme to transmit information via the statistical distribution of excitations of a nanomechanical resonator.It employs a controllable coupling between this system and a Cooper pair box.The success probability and the fidelity are calculated and compared with those obtained in an atom-field system in different regimes.Addtionaly,the scheme can also be applied to prepare low excited Fock states.

  12. Triplet pairing in neutron matter 21.65.+f; 26.60.+c; 74.20.Fg; Nucleonic superfluidity; Neutron stars; 3P2-3F2 pairing; Anisotropic pairing; Gap equations; Separation method

    CERN Document Server

    Khodel, V V; Clark, J W

    2001-01-01

    The separation method developed earlier by us [Nucl. Phys. A 598 390 (1996)] to calculate and analyze solutions of the BCS gap equation for sup 1 S sub 0 pairing is extended and applied to sup 3 P sub 2 - sup 3 F sub 2 pairing in pure neutron matter. The pairing matrix elements are written as a separable part plus a remainder that vanishes when either momentum variable is on the Fermi surface. This decomposition effects a separation of (i) the problem of determining the dependence of the gap components in a spin-angle representation on the magnitude of the momentum (described by a set of functions independent of magnetic quantum number) from (ii) the problem of determining the dependence of the gap on angle or magnetic projection. The former problem is solved through a set of nonsingular, quasilinear integral equations, providing inputs for solution of the latter problem through a coupled system of algebraic equations for a set of numerical coefficients. An incisive criterion is given for finding the upper cr...

  13. Hole states based on the {11}/{2}-[505] neutron orbital within the pairing gap

    Science.gov (United States)

    Peterson, R. J.; Garrett, J. D.

    1984-02-01

    Coupled-channel calculations have been performed for (d, p) and (d, t) reactions on the stable doubly even isotopes of Gd, Dy and Er for {11}/{2}- neutron transfer to the [505] band heads. Comparison to published data permitted reliable extraction of the occupation numbers for this orbital. The occupation numbers V2 were found to be much greater than the emptiness numbers U2, even for very low-lying excitations. These results can only be obtained for a very small pairing parameter, Δ, consistent with other less direct determinations. These results are as expected for a diminution of the pairing interaction for this oblate [505] orbital.

  14. Effects of Individual versus Paired/Cooperative Computer-Assisted Instruction on the Effectiveness and Efficiency of an In-Service Training Lesson.

    Science.gov (United States)

    Makuch, Joseph R.; And Others

    1992-01-01

    Describes a study that compared individual computer-assisted instruction (CAI) with paired/cooperative CAI as a method of providing inservice training for cooperative extension agents on the topic of proper water well location and construction. Cognitive achievement and time spent on the lesson are investigated. (18 references) (LRW)

  15. Collapse and revival of a single-Cooper-pair box in a single-mode quantized field

    Institute of Scientific and Technical Information of China (English)

    姚延荪; 邹健; 邵彬

    2003-01-01

    We study the quantum dynamics of a single-Cooper-pair box biased by a classical voltage and also irradiated by a single-mode quantized field.We demonstrate that under weak damping of the quantized field,the collapse-revival phenomena can exist in this system,and the oscillations of the collapse and revival depend sensitively on the initial state of the single-mode quantized field and the damping rate κ.We also demonstrate that this system can show the beats phenomena.

  16. Crossover between cooper-pair condensation and Bose condensation. Kupa tsui gyoshuku to Bose gyoshuku no crossover

    Energy Technology Data Exchange (ETDEWEB)

    Miyake, K. (Osaka Univ., Osaka (Japan). Faculty of Engineering and Science)

    1992-06-05

    When the effective attractions acting among electrons are strengthened gradually, the superconducting state at low temperature is thought to cross over from Cooper pairs condensation to the state of dielectronic compound boson Bose condensation. Firstly, the ground state is discussed. Nozieres {ampersand} Schmitt-Rink (NSR) have proposed a framework for discussion of transition temperature crossover by introducing the effect of pair fluctuation having finite moment. T {sub c} can be expressed by BCS expression for weak coupling, and by ideal Bose gas transition temperature expression for strong coupling. For the middle of the two extremity limits, NSR obtain numerical solution for a three dimensional case to show the transition temperature and smooth transition of chemical potential at the temperature. Namely, the NSR theory seems to be able to express the crossover of the transition temperature consistently. It has, however, difficulty in the application to two dimensional problems. 14 refs., 3 figs.

  17. Microfluidic application-specific integrated device for monitoring direct cell-cell communication via gap junctions between individual cell pairs

    Science.gov (United States)

    Lee, Philip J.; Hung, Paul J.; Shaw, Robin; Jan, Lily; Lee, Luke P.

    2005-05-01

    Direct cell-cell communication between adjacent cells is vital for the development and regulation of functional tissues. However, current biological techniques are difficult to scale up for high-throughput screening of cell-cell communication in an array format. In order to provide an effective biophysical tool for the analysis of molecular mechanisms of gap junctions that underlie intercellular communication, we have developed a microfluidic device for selective trapping of cell-pairs and simultaneous optical characterizations. Two different cell populations can be brought into membrane contact using an array of trapping channels with a 2μm by 2μm cross section. Device operation was verified by observation of dye transfer between mouse fibroblasts (NIH3T3) placed in membrane contact. Integration with lab-on-a-chip technologies offers promising applications for cell-based analytical tools such as drug screening, clinical diagnostics, and soft-state biophysical devices for the study of gap junction protein channels in cellular communications. Understanding electrical transport mechanisms via gap junctions in soft membranes will impact quantitative biomedical sciences as well as clinical applications.

  18. Highly Efficient Cooperative Catalysis by Co(III) (Porphyrin) Pairs in Interpenetrating Metal-Organic Frameworks.

    Science.gov (United States)

    Lin, Zekai; Zhang, Zhi-Ming; Chen, Yu-Sheng; Lin, Wenbin

    2016-10-24

    A series of porous twofold interpenetrated In-Co(III) (porphyrin) metal-organic frameworks (MOFs) were constructed by in situ metalation of porphyrin bridging ligands and used as efficient cooperative catalysts for the hydration of terminal alkynes. The twofold interpenetrating structure brings adjacent Co(III) (porphyrins) in the two networks parallel to each other with a distance of about 8.8 Å, an ideal distance for the simultaneous activation of both substrates in alkyne hydration reactions. As a result, the In-Co(III) (porphyrin) MOFs exhibit much higher (up to 38 times) catalytic activity than either homogeneous catalysts or MOF controls with isolated Co(III) (porphyrin) centers, thus highlighting the potential application of MOFs in cooperative catalysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A cavity-Cooper pair transistor scheme for investigating quantum optomechanics in the ultra-strong coupling regime

    Science.gov (United States)

    Rimberg, A. J.; Blencowe, M. P.; Armour, A. D.; Nation, P. D.

    2014-05-01

    We propose a scheme involving a Cooper pair transistor (CPT) embedded in a superconducting microwave cavity, where the CPT serves as a charge tunable quantum inductor to facilitate ultra-strong coupling between photons in the cavity and a nano- to meso-scale mechanical resonator. The mechanical resonator is capacitively coupled to the CPT, such that mechanical displacements of the resonator cause a shift in the CPT inductance and hence the cavity's resonant frequency. The amplification provided by the CPT is sufficient for the zero point motion of the mechanical resonator alone to cause a significant change in the cavity resonance. Conversely, a single photon in the cavity causes a shift in the mechanical resonator position on the order of its zero point motion. As a result, the cavity-Cooper pair transistor coupled to a mechanical resonator will be able to access a regime in which single photons can affect single phonons and vice versa. Realizing this ultra-strong coupling regime will facilitate the creation of non-classical states of the mechanical resonator, as well as the means to accurately characterize such states by measuring the cavity photon field.

  20. Cooperative Interactions in Peer Tutoring: Patterns and Sequences in Paired Writing

    Science.gov (United States)

    Duran, David

    2010-01-01

    The research analyzes the interaction of 24 students (12 pairs) of secondary students when using peer tutoring techniques to learn Catalan. Students worked together in a program to produce an authentic writing experience. Significant increases were observed in pre- and posttest Catalan attainment scores of students. An analysis of the…

  1. Performance measurement of the agricultural marketing cooperatives : The gap between theory and practice

    NARCIS (Netherlands)

    Soboh, R.A.M.E.; Oude Lansink, A.; Giesen, G.; Dijk, van G.

    2009-01-01

    The performance of agricultural cooperatives depends on their business objectives, which are defined in different ways in the literature. We review the theoretical literature on the performance of agricultural marketing cooperatives. Studies can be divided into two classes, those that assume a

  2. Doping-dependent critical Cooper-pair momentum pc in thin underdoped cuprate films

    Science.gov (United States)

    Lemberger, Thomas; Draskovic, John; Steers, Stanley; McJunkin, Thomas; Anmed, Adam

    2015-03-01

    We apply a low-field (oxygen stoichiometry through post-deposition annealing. The technique is based on applying a perpendicular magnetic field to the center of a superconducting film and measuring the field at which screening of the field catastrophically fails. Theory together with measurements on thin films of conventional superconductors Nb and MoGe argue for the validity of the technique. In underdoped cuprates, spectroscopy identifies multiple characteristic energy scales, e.g., the pseudogap and the ``nodal'' gap, neither of which is proportional to Tc. On general grounds, we expect to find that pc ~ 1/1ξ ξ is proportional to the characteristic superconducting energy scale. We observe that pc ~Tc as Tc decreases with underdoping, identifying kBTc as the characteristic energy. While this result is trivial in conventional superconductors whose spectroscopic gaps are proportional to Tc, it is significant in cuprates. Research supported by DOE-Basic Energy Sciences through Grant No. FG02-08ER46533.

  3. Breaking of nucleon Cooper pairs at finite temperature in 93-98Mo

    CERN Document Server

    Kaneko, K; Algin, E; Chankova, R; Guttormsen, M; Hasegawa, M; Larsen, A C; Mitchell, G E; Rekstad, J; Schiller, A; Siem, S; Voinov, A

    2006-01-01

    The S shape of the canonical heat capacity is known as a signature of the pairing transition and along an isotopic chain it is significantly more pronounced for nuclei with an even number of neutrons than with an odd number. Although the heat capacities extracted from experimental level densities in 93-98Mo exhibit a clear S shape, they do not show such an odd-even staggering. To understand the underlying physics, we analyze thermal quantities evaluated from the partition function calculated using the static-path plus random-phase approximation (SPA+RPA) in a monopole pairing model with number-parity projection. The calculated level densities reproduce very well the experimental data and they also agree with estimates using the back-shifted Fermi-gas model. We clarify the reason why the heat capacities for Mo isotopes do not show odd-even staggering of the S shape. We also discuss thermal odd-even mass differences in 94-97Mo using the three-, four-, and five-point formula. These thermal mass differences are r...

  4. Relay Selection and Subcarrier-Pair Based Energy-Efficient Resource Allocation for Multirelay Cooperative OFDMA Networks

    Directory of Open Access Journals (Sweden)

    Wanming Hao

    2014-01-01

    Full Text Available Energy-efficient resource allocation is investigated for a relay-based multiuser cooperation orthogonal frequency division multiple access (OFDMA uplink system with amplify-and-forward (AF protocol for all relays. The objective is to maximize the total energy efficiency (EE of the uplink system with consideration of some practical limitations, such as the individual power constraint for the users and relays and the quality of service (QoS for every user. We formulate an energy-efficient resource allocation problem that seeks joint optimization of subcarrier pairing, relay selection, subcarrier assignment, and power allocation. Unlike previous optimization throughput models, we transform the considered EE problem in fractional form into an equivalent optimal problem in subtractive form, which is solved by using dual decomposition and subgradient methods. To reduce computation costs, we propose two low-complexity suboptimal schemes. Numerical studies are conducted to evaluate the EE of the proposed algorithms.

  5. dREAM co-operates with insulator-binding proteins and regulates expression at divergently paired genes.

    Science.gov (United States)

    Korenjak, Michael; Kwon, Eunjeong; Morris, Robert T; Anderssen, Endre; Amzallag, Arnaud; Ramaswamy, Sridhar; Dyson, Nicholas J

    2014-08-01

    dREAM complexes represent the predominant form of E2F/RBF repressor complexes in Drosophila. dREAM associates with thousands of sites in the fly genome but its mechanism of action is unknown. To understand the genomic context in which dREAM acts we examined the distribution and localization of Drosophila E2F and dREAM proteins. Here we report a striking and unexpected overlap between dE2F2/dREAM sites and binding sites for the insulator-binding proteins CP190 and Beaf-32. Genetic assays show that these components functionally co-operate and chromatin immunoprecipitation experiments on mutant animals demonstrate that dE2F2 is important for association of CP190 with chromatin. dE2F2/dREAM binding sites are enriched at divergently transcribed genes, and the majority of genes upregulated by dE2F2 depletion represent the repressed half of a differentially expressed, divergently transcribed pair of genes. Analysis of mutant animals confirms that dREAM and CP190 are similarly required for transcriptional integrity at these gene pairs and suggest that dREAM functions in concert with CP190 to establish boundaries between repressed/activated genes. Consistent with the idea that dREAM co-operates with insulator-binding proteins, genomic regions bound by dREAM possess enhancer-blocking activity that depends on multiple dREAM components. These findings suggest that dREAM functions in the organization of transcriptional domains. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  6. Stressed Cooper pairing in dense QCD: effective Lagrangian and random matrix theory

    CERN Document Server

    Kanazawa, Takuya

    2014-01-01

    We generalize QCD at large isospin chemical potential to an arbitrary even number of flavors. We also allow for small quark chemical potentials, which stress the coincident Fermi surfaces of the paired quarks and lead to a sign problem in Monte Carlo simulations. We derive the corresponding low-energy effective theory in both $p$- and $\\varepsilon$-expansion and quantify the severity of the sign problem. We construct the random matrix theory describing our physical situation and show that it can be mapped to a known random matrix theory at low density so that new insights can be gained without additional calculations. In particular, we explain the Silver Blaze phenomenon at high density. We also introduce stressed singular values of the Dirac operator and relate them to the pionic condensate. Finally we comment on extensions of our work to two-color QCD.

  7. Stressed Cooper pairing in QCD at high isospin density: effective Lagrangian and random matrix theory

    Science.gov (United States)

    Kanazawa, Takuya; Wettig, Tilo

    2014-10-01

    We generalize QCD at asymptotically large isospin chemical potential to an arbitrary even number of flavors. We also allow for small quark chemical potentials, which stress the coincident Fermi surfaces of the paired quarks and lead to a sign problem in Monte Carlo simulations. We derive the corresponding low-energy effective theory in both p- and ɛ-expansion and quantify the severity of the sign problem. We construct the random matrix theory describing our physical situation and show that it can be mapped to a known random matrix theory at low baryon density so that new insights can be gained without additional calculations. In particular, we explain the Silver Blaze phenomenon at high isospin density. We also introduce stressed singular values of the Dirac operator and relate them to the pionic condensate. Finally we comment on extensions of our work to two-color QCD.

  8. A subcarrier-pair based resource allocation scheme using proportional fairness for cooperative OFDM-based cognitive radio networks.

    Science.gov (United States)

    Ma, Yongtao; Zhou, Liuji; Liu, Kaihua

    2013-08-09

    The paper presents a joint subcarrier-pair based resource allocation algorithm in order to improve the efficiency and fairness of cooperative multiuser orthogonal frequency division multiplexing (MU-OFDM) cognitive radio (CR) systems. A communication model where one source node communicates with one destination node assisted by one half-duplex decode-and-forward (DF) relay is considered in the paper. An interference-limited environment is considered, with the constraint of transmitted sum-power over all channels and aggregate average interference towards multiple primary users (PUs). The proposed resource allocation algorithm is capable of maximizing both the system transmission efficiency and fairness among secondary users (SUs). Besides, the proposed algorithm can also keep the interference introduced to the PU bands below a threshold. A proportional fairness constraint is used to assure that each SU can achieve a required data rate, with quality of service guarantees. Moreover, we extend the analysis to the scenario where each cooperative SU has no channel state information (CSI) about non-adjacent links. We analyzed the throughput and fairness tradeoff in CR system. A detailed analysis of the performance of the proposed algorithm is presented with the simulation results.

  9. The halo of the exotic nucleus $^{11}Li$ : a single Cooper pair

    CERN Document Server

    Barranco, F; Colò, G; Vigezzi, E

    2000-01-01

    If neutrons are progressively added to a normal nucleus, the Pauli principle forces them into states of higher momentum. When the core becomes neutron-saturated, the nucleus expels most of the wavefunction of the last neutrons outside to form a halo, which because of its large size can have lower momentum. It is an open question how nature stabilizes such a fragile system and provides the glue needed to bind the halo neutrons to the core. Here we show that this problem is similar to that of the instability of the normal state of an electron system at zero temperature solved by Cooper, solution which is at the basis of BCS theory of superconductivity. By mimicking this approach using, aside from the bare nucleon-nucleon interaction, the long wavelength vibrations of the nucleus $^{11}$Li, the paradigm of halo nuclei, as tailored glues of the least bound neutrons, we are able to obtain a unified and quantitative picture of the observed properties of $^{11}$Li. This result suggests a strategy for designing nucle...

  10. Paramagnetic Cooper pair breaking effect in α-(BEDT-TTF){sub 2}KHg(SCN){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, Michael; Jakob, Sebastian; Biberacher, Werner; Neumaier, Karl; Kartsovnik, Mark V. [Walther-Meissner-Institut, Garching (Germany); Mueller, Harald [European Synchrotron Radiation Facility, Grenoble (France)

    2013-07-01

    The organic charge transfer salt α-(BEDT-TTF){sub 2}KHg(SCN){sub 4} is a quasi-two-dimensional metal consisting of conducting and insulating layers. At pressures above 2.5 kbar this compound features a low T{sub c} (∝0.1 K) superconducting state with an unprecedentedly high anisotropy of the upper critical field depending on whether the magnetic field is oriented parallel or perpendicular to the conducting planes. This is due to a strong suppression of the superconducting shielding currents in the direction perpendicular to the layers. For an exact parallel field orientation the shielding currents become so weak that their effect is replaced by the Pauli paramagnetic effect as the main contribution to the Cooper pair breaking. Clear manifestations of the paramagnetic pair breaking can be seen in the temperature dependence as well as in the angular dependence of the critical field near parallel orientation. At the exact parallel field orientation, the theoretical Chandrasekhar-Clogston paramagnetic limit is exceeded by a factor of 1.3, most likely due to a strong electron-phonon coupling. From the analysis of the temperature dependence of the parallel critical field the Maki parameter can be determined.

  11. Spectral density of Cooper pairs in two level quantum dot–superconductors Josephson junction

    Energy Technology Data Exchange (ETDEWEB)

    Dhyani, A., E-mail: archana.d2003@gmail.com [Department of Physics, University of Petroleum and Energy Studies, Dehradun 248007, Uttarakhand (India); Rawat, P.S. [Department of Nuclear Science and Technology, University of Petroleum and Energy Studies, Dehradun 248007, Uttarakhand (India); Tewari, B.S., E-mail: bstewari@ddn.upes.ac.in [Department of Physics, University of Petroleum and Energy Studies, Dehradun 248007, Uttarakhand (India)

    2016-09-15

    Highlights: • The present work deals with the study of the electronic spectral density of electron pairs and its effect in charge transport in superconductor-quantum dot-superconductor junctions. • The charge transfer across such junctions can be controlled by changing the positions of the dot level. • The Josephson supercurrent can also be tuned by controlling the position of quantum dot energy levels. - Abstract: In the present paper, we report the role of quantum dot energy levels on the electronic spectral density for a two level quantum dot coupled to s-wave superconducting leads. The theoretical arguments in this work are based on the Anderson model so that it necessarily includes dot energies, single particle tunneling and superconducting order parameter for BCS superconductors. The expression for single particle spectral function is obtained by using the Green's function equation of motion technique. On the basis of numerical computation of spectral function of superconducting leads, it has been found that the charge transfer across such junctions can be controlled by the positions and availability of the dot levels.

  12. Bridging the Gap between Education & Practice: A Cooperative Effort between Education and Service.

    Science.gov (United States)

    Hutcherson, Annette H.

    1986-01-01

    Looks at inservice and educational solutions to the problem of reality shock (i.e., conflict between the values of school and work) in the nursing profession. Describes a cooperative education-service program, which focuses on role expectation, competency, the health care system, and self-concept in a concentrated, comprehensive clinical…

  13. Superconducting properties and pseudogap from preformed Cooper pairs in the triclinic (CaFe1-xPtxAs ) 10Pt3As8

    Science.gov (United States)

    Surmach, M. A.; Brückner, F.; Kamusella, S.; Sarkar, R.; Portnichenko, P. Y.; Park, J. T.; Ghambashidze, G.; Luetkens, H.; Biswas, P. K.; Choi, W. J.; Seo, Y. I.; Kwon, Y. S.; Klauss, H.-H.; Inosov, D. S.

    2015-03-01

    Using a combination of muon-spin relaxation (μ SR ) , inelastic neutron scattering (INS), and nuclear magnetic resonance (NMR), we investigated the novel iron-based superconductor with a triclinic crystal structure (CaFe1-xPtxAs ) 10Pt3As8 (Tc=13 K), containing platinum-arsenide intermediary layers. The temperature dependence of the superfluid density obtained from the μ SR relaxation-rate measurements indicates the presence of two superconducting gaps, Δ1≫Δ2 . According to our INS measurements, commensurate spin fluctuations are centered at the (π ,0 ) wave vector, like in most other iron arsenides. Their intensity remains unchanged across Tc, indicating the absence of a spin resonance typical for many Fe-based superconductors. Instead, we observed a peak in the spin-excitation spectrum around ℏ ω0=7 meV at the same wave vector, which persists above Tc and is characterized by the ratio ℏ ω0/kBTc≈6.2 , which is significantly higher than typical values for the magnetic resonant modes in iron pnictides (˜4.3 ) . The temperature dependence of magnetic intensity at 7 meV revealed an anomaly around T*=45 K related to the disappearance of this new mode. A suppression of the spin-lattice relaxation rate, 1 /T1T , observed by NMR immediately below T* without any notable subsequent anomaly at Tc, indicates that T* could mark the onset of a pseudogap in (CaFe1-xPtxAs ) 10Pt3As8 , which is likely associated with the emergence of preformed Cooper pairs.

  14. Hybrid germanium iodide perovskite semiconductors: active lone pairs, structural distortions, direct and indirect energy gaps, and strong nonlinear optical properties.

    Science.gov (United States)

    Stoumpos, Constantinos C; Frazer, Laszlo; Clark, Daniel J; Kim, Yong Soo; Rhim, Sonny H; Freeman, Arthur J; Ketterson, John B; Jang, Joon I; Kanatzidis, Mercouri G

    2015-06-03

    The synthesis and properties of the hybrid organic/inorganic germanium perovskite compounds, AGeI3, are reported (A = Cs, organic cation). The systematic study of this reaction system led to the isolation of 6 new hybrid semiconductors. Using CsGeI3 (1) as the prototype compound, we have prepared methylammonium, CH3NH3GeI3 (2), formamidinium, HC(NH2)2GeI3 (3), acetamidinium, CH3C(NH2)2GeI3 (4), guanidinium, C(NH2)3GeI3 (5), trimethylammonium, (CH3)3NHGeI3 (6), and isopropylammonium, (CH3)2C(H)NH3GeI3 (7) analogues. The crystal structures of the compounds are classified based on their dimensionality with 1–4 forming 3D perovskite frameworks and 5–7 1D infinite chains. Compounds 1–7, with the exception of compounds 5 (centrosymmetric) and 7 (nonpolar acentric), crystallize in polar space groups. The 3D compounds have direct band gaps of 1.6 eV (1), 1.9 eV (2), 2.2 eV (3), and 2.5 eV (4), while the 1D compounds have indirect band gaps of 2.7 eV (5), 2.5 eV (6), and 2.8 eV (7). Herein, we report on the second harmonic generation (SHG) properties of the compounds, which display remarkably strong, type I phase-matchable SHG response with high laser-induced damage thresholds (up to ∼3 GW/cm(2)). The second-order nonlinear susceptibility, χS(2), was determined to be 125.3 ± 10.5 pm/V (1), (161.0 ± 14.5) pm/V (2), 143.0 ± 13.5 pm/V (3), and 57.2 ± 5.5 pm/V (4). First-principles density functional theory electronic structure calculations indicate that the large SHG response is attributed to the high density of states in the valence band due to sp-hybridization of the Ge and I orbitals, a consequence of the lone pair activation.

  15. Coexistence of localization and superconductivity in underdoped BSCCO: Are the Cooper pairs formed by spatially localized carriers?

    Science.gov (United States)

    Beschoten, B.; Güntherodt, G.; Quitmann, C.; Ma, Jian; Kelley, R. J.; Onellion, M.; Almeras, P.; Berger, H.; Margaritondo, H.

    1998-03-01

    In underdoped Bi_2Sr_2CaCu_2Oy we relate changes in the electronic structure seen in angle-resolved photoemission (ARPES) to changes in the electronic transport. The substitution of Pr for Ca or Co for Cu induces potential disorder leading to spatial localization of electronic states near the Fermi level for T>T_c. This indicates that Cooper pairs are formed by spatially localized electronic states. An anisotropic one-band model is given suggesting that localization seen in transport (ρ and μ(T)=R_H(T)/ρ(T)) for T>Tc can either be isotropic in k-space as for Co/Cu doping or anisotropic as for Pr/Ca doping. Spectroscopic evidence for this anisotropy is given by ARPES. Localization seen in ρ and μ, respectively, correlates with a supression of the band dispersion of electronic states along the symmetry directions in k-space from (0,0) to (0,π) and to (π,π). Supported by DFG/SFB 341, U.S. NSF.

  16. Thermodynamic study of gap structure and pair-breaking effect by magnetic field in the heavy-fermion superconductor CeCu2Si2

    Science.gov (United States)

    Kittaka, Shunichiro; Aoki, Yuya; Shimura, Yasuyuki; Sakakibara, Toshiro; Seiro, Silvia; Geibel, Christoph; Steglich, Frank; Tsutsumi, Yasumasa; Ikeda, Hiroaki; Machida, Kazushige

    2016-08-01

    This paper presents the results of specific-heat and magnetization measurements, in particular their field-orientation dependence, on the first discovered heavy-fermion superconductor CeCu2Si2 (Tc˜0.6 K). We discuss the superconducting gap structure and the origin of the anomalous pair-breaking phenomena, leading, e.g., to the suppression of the upper critical field Hc 2, found in the high-field region. The data show that the anomalous pair breaking becomes prominent below about 0.15 K in any field direction, but occurs closer to Hc 2 for H ∥c . The presence of this anomaly is confirmed by the fact that the specific-heat and magnetization data satisfy standard thermodynamic relations. Concerning the gap structure, field-angle dependencies of the low-temperature specific heat within the a b and a c planes do not show any evidence for gap nodes. From microscopic calculations in the framework of a two-band full-gap model, the power-law-like temperature dependencies of C and 1 /T1 , reminiscent of nodal superconductivity, have been reproduced reasonably. These facts further support multiband full-gap superconductivity in CeCu2Si2 .

  17. Malaria Status in Economic Cooperation Countries; Achievement and Gaps Toward United Nations Millennium Development Goals

    Directory of Open Access Journals (Sweden)

    A Mirzazadeh

    2012-07-01

    Full Text Available Background: Evaluating the malaria status of the Economic Cooperation Organization (ECO member countries relation to goal 6 of 3rd Millennium Development Goals (MDGs which includes have halted by 2015 and begun to reverse the incidence of malaria.Methods: By 2009, we reviewed the MDGs reports, extracted the data from surveillance system, published, and unpublished data. The main stakeholders, from both governmental and international organizations in the country have been visited and interviewed by the research team as part of the data validation process.Results: The malaria incidence is very heterogeneous among ECO countries, which differ less than 200 cases in total country in Kazakhstan, Kyrgyzstan, Turkey, Turkmenistan, Uzbekistan, and Azerbaijan to 82,564 cases (2,428/100,000 in Afghanistan and 59,284 cases (881/100,000 in Pakistan and about 18/100,000 in Iran in 2008. Malaria has been a major public health problem in Pakistan and Afghanistan and will continue to pose serious threat to millions of people due to poor environmental and socioeconomic conditions conducive to the spread of disease. The main malaria endemic areas of Iran are in southeastern part of the country; consist of less developed provinces that are bordered in the east by Afghanistan and Pakistan. There are little valid information about proportion of population in malaria-risk areas using effective malaria prevention and treatment measures indicators.Conclusion: All ECO countries could achieve MDGs malaria indicators by 2015 except Pakistan and Afghanistan, unless preparing urgent intervention programs to fulfill the goals.

  18. Detecting and estimating rectification of gap junction conductance based on simulations of dual-cell recordings from a pair and a network of coupled cells.

    Science.gov (United States)

    Fortier, Pierre A

    2010-07-21

    Gap junctions can exhibit rectification of conductance. Some reports use inequality of coupling coefficients as the first sign of the possible existence of rectification (Devor and Yarom, 2002; Fan et al., 2005; Levavi-Sivan et al., 2005; Mann-Metzer and Yarom, 1999; Nolan et al., 1999; Szabadics et al., 2001). However, mathematical modeling and simulations of electrotonic coupling between an isolated pair of neurons showed conditions where the coupling coefficients were unreliable indicators of rectification. On the other hand, the transfer resistances were found to be reliable indicators of junctional rectification. The existing mathematical model of cell coupling (Bennett, 1966; Devor and Yarom, 2002; Verselis and Veenstra, 2000) was extended in order to measure rectification of the junctional conductances directly between dual-recorded neurons whether isolated or surrounded by a simulated 3-dimensional network of heterogeneous cells whose gap junctions offered parallel paths for current flow between the recorded neurons. The results showed that the transfer resistances could still detect rectification of the gap junction linking the dual-recorded neurons when embedded in a coupled cell network and that a mathematical model could estimate the conductances in both directions through this gap junction using only data that would be available from real dual-intracellular penetrations which allow electrophysiological recordings and intracellular staining. Rectification of gap junctions in unrecorded cells of a biologically realistic coupled cell network had negligible effects on the voltage responses of the dual-recorded neurons because of minimal current passing through these surrounding cells.

  19. Elucidating the structures and cooperative binding mechanism of cesium salts to the multitopic ion-pair receptor through density functional theory calculations.

    Science.gov (United States)

    Sadhu, Biswajit; Sundararajan, Mahesh; Velmurugan, Gunasekaran; Venuvanalingam, Ponnambalam

    2015-09-21

    Designing new and innovative receptors for the selective binding of radionuclides is central to nuclear waste management processes. Recently, a new multi-topic ion-pair receptor was reported which binds a variety of cesium salts. Due to the large size of the receptor, quantum chemical calculations on the full ion-pair receptors are restricted, thus the binding mechanisms are not well understood at the molecular level. We have assessed the binding strengths of various cesium salts to the recently synthesized multi-topic ion-pair receptor molecule using density functional theory based calculations. Our calculations predict that the binding of cesium salts to the receptor predominantly occurs via the cooperative binding mechanism. Cesium and the anion synergistically assist each other to bind favorably inside the receptor. Energy decomposition analysis on the ion-pair complexes shows that the Cs salts are bound to the receptor mainly through electrostatic interactions with small contribution from covalent interactions for large ionic radius anions. Further, QTAIM analysis characterizes the importance of different inter-molecular interactions between the ions and the receptor inside the ion-pair complexes. The role of the crystallographic solvent molecule contributes significantly by ~10 kcal mol(-1) to the overall binding affinities which is quite significant. Further, unlike the recent molecular mechanics (MM) calculations, our calculated binding affinity trends for various Cs ion-pair complexes (CsF, CsCl and CsNO3) are now in excellent agreement with the experimental binding affinity trends.

  20. Unconventional High-Energy-State Contribution to the Cooper Pairing in the Underdoped Copper-Oxide Superconductor HgBa_{2}Ca_{2}Cu_{3}O_{8+δ}.

    Science.gov (United States)

    Loret, B; Sakai, S; Gallais, Y; Cazayous, M; Méasson, M-A; Forget, A; Colson, D; Civelli, M; Sacuto, A

    2016-05-13

    We study the temperature-dependent electronic B_{1g} Raman response of a slightly underdoped single crystal HgBa_{2}Ca_{2}Cu_{3}O_{8+δ} with a superconducting critical temperature T_{c}=122  K. Our main finding is that the superconducting pair-breaking peak is associated with a dip on its higher-energy side, disappearing together at T_{c}. This result reveals a key aspect of the unconventional pairing mechanism: spectral weight lost in the dip is transferred to the pair-breaking peak at lower energies. This conclusion is supported by cellular dynamical mean-field theory on the Hubbard model, which is able to reproduce all the main features of the B_{1g} Raman response and explain the peak-dip behavior in terms of a nontrivial relationship between the superconducting gap and the pseudogap.

  1. Unconventional High-Energy-State Contribution to the Cooper Pairing in the Underdoped Copper-Oxide Superconductor HgBa2 Ca2 Cu3 O8 +δ

    Science.gov (United States)

    Loret, B.; Sakai, S.; Gallais, Y.; Cazayous, M.; Méasson, M.-A.; Forget, A.; Colson, D.; Civelli, M.; Sacuto, A.

    2016-05-01

    We study the temperature-dependent electronic B1 g Raman response of a slightly underdoped single crystal HgBa2 Ca2 Cu3 O8 +δ with a superconducting critical temperature Tc=122 K . Our main finding is that the superconducting pair-breaking peak is associated with a dip on its higher-energy side, disappearing together at Tc. This result reveals a key aspect of the unconventional pairing mechanism: spectral weight lost in the dip is transferred to the pair-breaking peak at lower energies. This conclusion is supported by cellular dynamical mean-field theory on the Hubbard model, which is able to reproduce all the main features of the B1 g Raman response and explain the peak-dip behavior in terms of a nontrivial relationship between the superconducting gap and the pseudogap.

  2. Triplet Cooper pairs induced in diffusive s-wave superconductors interfaced with strongly spin-polarized magnetic insulators or half-metallic ferromagnets.

    Science.gov (United States)

    Ouassou, Jabir Ali; Pal, Avradeep; Blamire, Mark; Eschrig, Matthias; Linder, Jacob

    2017-05-16

    Interfacing superconductors with strongly spin-polarized magnetic materials opens the possibility to discover new spintronic devices in which spin-triplet Cooper pairs play a key role. Motivated by the recent derivation of spin-polarized quasiclassical boundary conditions capable of describing such a scenario in the diffusive limit, we consider the emergent physics in hybrid structures comprised of a conventional s-wave superconductor (e.g. Nb, Al) and either strongly spin-polarized ferromagnetic insulators (e.g. EuO, GdN) or halfmetallic ferromagnets (e.g. CrO2, LCMO). In contrast to most previous works, we focus on how the superconductor itself is influenced by the proximity effect, and how the generated triplet Cooper pairs manifest themselves in the self-consistently computed density of states (DOS) and the superconducting critical temperature T c . We provide a comprehensive treatment of how the superconductor and its properties are affected by the triplet pairs, demonstrating that our theory can reproduce the recent observation of an unusually large zero-energy peak in a superconductor interfaced with a half-metal, which even exceeds the normal-state DOS. We also discuss the recent observation of a large superconducting spin-valve effect with a T c change ~1 K in superconductor/half-metal structures, in which case our results indicate that the experiment cannot be explained fully by a long-ranged triplet proximity effect.

  3. Evolution of cooperation in the snowdrift game among mobile players with random-pairing and reinforcement learning

    Science.gov (United States)

    Jia, Ning; Ma, Shoufeng

    2013-11-01

    The evolutionary spatial game in a mobile population has attracted many researchers of biological, social and economic sciences. Considering some facts observed in the real world, this paper proposes a novel spatial evolutionary snowdrift game model with movable players. In this model, one player interacts only with the nearest neighbor in each turn, and makes decision in a reinforcement learning way. In a very large range of the parameters moving ability enhances cooperation, but under some special condition, velocity heavily depresses cooperation. Some explanations have also been given out by investigating the strategy-change behavior of players. The findings may be helpful in understanding cooperative behavior in natural and social systems consisting of mobile agents.

  4. The Effect of Cooperative Learning Model Script and Think-Pair-Share to Critical Thinking Skills, Social Attitude and Learning Outcomes Cognitive Biology of multiethnic High School Students

    Directory of Open Access Journals (Sweden)

    Didimus Tanah Boleng

    2015-03-01

    Full Text Available Pengaruh Model Pembelajaran Cooperative Script dan Think-Pair-Share terhadap Keterampilan Berpikir Kritis, Sikap Sosial, dan Hasil Belajar Kognitif Biologi Siswa SMA Multietnis   Abstract: Biological learning process with multiethnic students requires a learning models which allow students to work independently, to work together in small groups, and to share with other groups. The purpose of this study was to determine the effect of learning models, ethnicity, and the interaction of learning model and ethnic on critical thinking skills, social attitudes, and cognitive achievement. This quasi experimental study was conducted in 11th grade of Natural Science Class Highschool students with six ethnicaly and Junior Highschool National score groups consisted of 132 samples. The results of Covarian Analysis showed that the learning models significantly affected the social attitudes and increased the critical thinking skills and cognitive achievement. Ethnicity significantly affected the social attitudes and cognitive achievement. Interaction of learning models and ethnicity significantly affected students social attitudes. Key Words: cooperative script, think-pair-share, critical thinking skills, social attitudes, biology cognitive achievement, multiethnic students Abstrak: Pengelolaan proses pembelajaran biologi pada siswa multietnis memerlukan model pembelajaran yang memungkinkan siswa bekerja mandiri, bekerja sama dalam kelompok kecil, dan berbagi dengan kelompok lain. Tujuan penelitian ini untuk mengetahui pengaruh model pembelajaran, etnis, serta interaksi model pembelajaran dan etnis terhadap keterampilan berpikir kritis, sikap sosial, dan hasil belajar kognitif biologi siswa. Penelitian eksperimen semu ini dilakukan di kelas XI IPA SMA dengan sampel sebanyak 132 orang siswa terbagi dalam enam kelas yang homogen berdasarkan etnis dan nilai ujian nasional SMP siswa. Hasil analisis data dengan menggunakan Analisis Kovarian menunjukkan bahwa model

  5. 78 FR 55296 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-American Gap...

    Science.gov (United States)

    2013-09-10

    ... ratification of industry standards for Gap Year Education, the further development of a Board of Advisors, and... Gap Association Notice is hereby given that, on August 12, 2013, pursuant to Section 6(a) of the... Gap Association (``AGA'') has filed written notifications simultaneously with the Attorney General...

  6. In situ synthesis of porous array films on a filament induced micro-gap electrode pair and their use as resistance-type gas sensors with enhanced performances.

    Science.gov (United States)

    Xu, Zongke; Duan, Guotao; Zhang, Hongwen; Wang, Yingying; Xu, Lei; Cai, Weiping

    2015-09-14

    Resistance-type metal-oxide semiconductor gas sensors with high sensitivity and low detection limit have been explored for practical applications. They require both sensing films with high sensitivity to target gases and an appropriate structure of the electrode-equipped substrate to support the sensing films, which is still challenging. In this paper, a new gas sensor of metal-oxide porous array films on a micro-gap electrode pair is designed and implemented by taking ZnO as a model material. First, a micro-gap electrode pair was constructed by sputtering deposition on a filament template, which was used as the sensor's supporting substrate. Then, the sensing film, made up of ZnO porous periodic arrays, was in situ synthesized onto the supporting substrate by a solution-dipping colloidal lithography strategy. The results demonstrated the validity of the strategy, and the as-designed sensor shows a small device-resistance, an enhanced sensing performance with high resolution and an ultralow detection limit. This work provides an alternative method to promote the practical application of resistance-type gas sensors.

  7. Pairing reentrance in warm rotating $^{104}$Pd nucleus

    CERN Document Server

    Hung, N Quang; Agrawal, B K; Datar, V M; Mitra, A; Chakrabarty, D R

    2015-01-01

    Pairing reentrance phenomenon in the warm rotating $^{104}$Pd nucleus is studied within the Bardeen-Cooper-Schrieffer (BCS)-based approach (the FTBCS1). The theory takes into account the effect of quasiparticle number fluctuations on the pairing field at finite temperature and angular momentum within the pairing model plus noncollective rotation along the symmetry axis. The numerical calculations for the pairing gaps and nuclear level densities (NLD), of which an anomalous enhancement has been experimentally observed at low excitation energy $E^*$ and high angular momentum $J$, show that the pairing reentrance is seen in the behavior of pairing gap obtained within the FTBCS1 at low $E$ and high $J$. This leads to the enhancement of the FTBCS1 level densities, in good agreement with the experimental observation. This agreement indicates that the observed enhancement of the NLD might be the first experimental detection of the pairing reentrance in a finite nucleus.

  8. Highly Efficient Cooperative Catalysis by Co III (Porphyrin) Pairs in Interpenetrating Metal-Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zekai; Zhang, Zhi-Ming; Chen, Yu-Sheng; Lin, Wenbin (UC); (Xiamen)

    2016-12-02

    A series of porous twofold interpenetrated In-CoIII(porphyrin) metal–organic frameworks (MOFs) were constructed by in situ metalation of porphyrin bridging ligands and used as efficient cooperative catalysts for the hydration of terminal alkynes. The twofold interpenetrating structure brings adjacent CoIII(porphyrins) in the two networks parallel to each other with a distance of about 8.8 Å, an ideal distance for the simultaneous activation of both substrates in alkyne hydration reactions. As a result, the In-CoIII(porphyrin) MOFs exhibit much higher (up to 38 times) catalytic activity than either homogeneous catalysts or MOF controls with isolated CoIII(porphyrin) centers, thus highlighting the potential application of MOFs in cooperative catalysis.

  9. Dual origin of pairing in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Idini, A. [University of Jyvaskyla, Department of Physics (Finland); Potel, G. [Michigan State University, National Superconducting Cyclotron Laboratory (United States); Barranco, F. [Escuela Superior de Ingenieros, Universidad de Sevilla, Departamento de Fìsica Aplicada III (Spain); Vigezzi, E., E-mail: enrico.vigezzi@mi.infn.it [INFN Sezione di Milano (Italy); Broglia, R. A. [Università di Milano, Dipartimento di Fisica (Italy)

    2016-11-15

    The pairing correlations of the nucleus {sup 120}Sn are calculated by solving the Nambu–Gor’kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong {sup 1}S{sub 0} short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- (v{sub p}{sup bare}) and long-range (v{sub p}{sup ind}) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.

  10. Gap bridging enhancement of modified Urca process in nuclear matter

    CERN Document Server

    Alford, Mark G

    2016-01-01

    In nuclear matter at neutron-star densities and temperatures, Cooper pairing leads to the formation of a gap in the nucleon excitation spectra resulting in exponentially strong Boltzmann suppression of many transport coefficients. Previous calculations have shown evidence that density oscillations of sufficiently large amplitude can overcome this suppression for flavor-changing beta processes, via the mechanism of "gap bridging". We address the simplifications made in that initial work, and show that gap bridging can counteract Boltzmann suppression of neutrino emissivity for the realistic case of modified Urca processes in matter with $^3P_2$ neutron pairing.

  11. Cooperative effect by monopodal silica-supported niobium com-plexes pairs enhancing catalytic cyclic carbonate production

    KAUST Repository

    D'Elia, Valerio

    2015-05-07

    Recent discoveries highlighted the activity and the intriguing mechanistic features of NbCl5 as a molecular catalyst for the cycloaddition of CO2 and epoxides under ambient conditions. This has inspired the preparation of novel silica supported Nb-species by reacting a molecular niobium precursor [NbCl5•OEt2] with silica dehydroxylated at 700 °C (SiO2-700) or at 200 oC (SiO2-200) to generate diverse surface complexes. The product of the reaction between SiO2-700 and [NbCl5•OEt2] was identified as a monopodal supported surface species [≡SiONbCl4•OEt2] (1a). The reactions of SiO2-200 with the niobium precursor, according to two different protocols, generated surface complexes 2a and 3a presenting significant, but different, populations of the monopodal surface complex along with bipodal [(≡SiO)2NbCl3•OEt2]. 93Nb SSNMR spectra of 1a-3a and 31P SSNMR on their PMe3 derivatives (1b-3b) led to the unambiguous assignment of 1a as a single site, monopodal Nb-species while 2a and 3a were found to present two distinct surface-supported components, with 2a being mostly monopodal [≡SiONbCl4•OEt2] and 3a being mostly bipodal [≡S ONbCl3•OEt2]. Double-quantum/single-quantum 31P NMR correlation experiment carried out on 2b supported the existence of vicinal Nb centers on the silica surface for this species. 1a-3a were active heterogeneous catalysts for the synthesis of propylene carbonate from CO2 and propylene oxide under mild catalytic conditions; the performance of 2a was found to significantly surpass that of 1a and 3a. With the support of a systematic DFT study carried out on model silica surfaces, the observed differences in catalytic efficiency were correlated with an unprece-dented cooperative effect between two neighboring Nb centers on the surface of 2a. This is in an excellent agreement with our previous discoveries regarding the mechanism of the NbCl5 catalyzed cycloaddition in the homogeneous phase.

  12. Superconducting properties and pseudogap from preformed Cooper pairs in the triclinic (CaFe{sub 1-x}Pt{sub x}As){sub 10}Pt{sub 3}As{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Surmach, M.A.; Brueckner, F.; Kamusella, S.; Sarkar, R.; Portnichenko, P.Y.; Klauss, H.H.; Inosov, D.S. [TU Dresden (Germany); Park, J.T. [MLZ, Garching (Germany); Ghambashidze, G. [MPI, Stuttgart (Germany); Luetkens, H.; Biswas, P. [PSI, Villigen (Switzerland); Choi, W.J.; Seo, Y.I.; Kwon, Y.S. [DGIST, Daegu (Korea, Republic of)

    2015-07-01

    Using μSR, INS and NMR, we investigated the novel Fe-based superconductor with a triclinic crystal structure (CaFe{sub 1-x}Pt{sub x}As){sub 10}Pt{sub 3}As{sub 8} (T{sub c}=13 K). The T-dependence of the superfluid density from the μSR measurements indicates the presence of two superconducting gaps. Our INS data revealed commensurate spin fluctuations at the (π, 0) wave vector. Their intensity remains unchanged across T{sub c}, indicating the absence of a spin resonance typical for many Fe-pnictides. Instead, we observed a peak around ℎω{sub 0} = 7 meV at the same wave vector, which persists above T{sub c} and is characterized by the ratio ℎω{sub 0}/k{sub B}T{sub c}∼6.2, i.e. significantly higher than typical values for the magnetic resonant modes in iron pnictides (∝ 4.3). The T-dependence of magnetic intensity at 7 meV revealed an anomaly around T*=45 K related to the disappearance of this new mode. A suppression of the spin-lattice relaxation rate, 1=/T{sub 1}T, observed by NMR immediately below T* without any notable subsequent anomaly at T{sub c}, indicates that T{sup *} could mark the onset of a pseudogap in (CaFe{sub 1-x}Pt{sub x}As){sub 10}Pt{sub 3}As{sub 8}, likely associated with the emergence of preformed Cooper pairs.

  13. Gap Resolution

    Energy Technology Data Exchange (ETDEWEB)

    2017-04-25

    Gap Resolution is a software package that was developed to improve Newbler genome assemblies by automating the closure of sequence gaps caused by repetitive regions in the DNA. This is done by performing the follow steps:1) Identify and distribute the data for each gap in sub-projects. 2) Assemble the data associated with each sub-project using a secondary assembler, such as Newbler or PGA. 3) Determine if any gaps are closed after reassembly, and either design fakes (consensus of closed gap) for those that closed or lab experiments for those that require additional data. The software requires as input a genome assembly produce by the Newbler assembler provided by Roche and 454 data containing paired-end reads.

  14. Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

    Directory of Open Access Journals (Sweden)

    Y.-B. Huang

    2012-12-01

    Full Text Available The superconducting gap is the fundamental parameter that characterizes the superconducting state, and its symmetry is a direct consequence of the mechanism responsible for Cooper pairing. Here we discuss about angle-resolved photoemission spectroscopy measurements of the superconducting gap in the Fe-based high-temperature superconductors. We show that the superconducting gap is Fermi surface dependent and nodeless with small anisotropy, or more precisely, a function of the momentum location in the Brillouin zone. We show that while this observation seems inconsistent with weak coupling approaches for superconductivity in these materials, it is well supported by strong coupling models and global superconducting gaps. We also suggest that a smaller lifetime of the superconducting Cooper pairs induced by the momentum dependent interband scattering inherent to these materials could affect the residual density of states at low energies, which is critical for a proper evaluation of the superconducting gap.

  15. Crossover from pseudogap to superconducting gap

    CERN Document Server

    De Cao, Tian

    2010-01-01

    The pseudogap is one of the most pervasive phenomena of high temperature superconductors [1, 2]. There exist two main theoretical scenarios for the explanation of the pseudogap. One is based upon the model of Cooper pairs formation already above the critical temperature of superconducting transition [3, 4], while another assumes that the appearance of the pseudogap state is due to the other orders [5, 6, 7]. Here we find that the particular electronic structure of cuprates confines Cooper pairs to be firstly formed around the antinodal region which is far from the Fermi surface, and these pairs are incoherent and result in the pseudogap state. With the change of doping or temperature, some pairs are transferred toward the nodal region which is on the Fermi surface, thus these pairs are coherent and lead to superconductivity. Thus the coexistence of the pseudogap and the superconducting gap is explained when these two kinds of gaps are not all on the Fermi surface. It is also shown that the symmetry of the pse...

  16. Sanderson's electronegative equalization principle and Cooper pair electrons%Sanderson's电负性均衡原理与库柏对电子

    Institute of Scientific and Technical Information of China (English)

    黄新民; 陈羽

    2011-01-01

    In this paper, based on the electrons mediums phonons mechanism, the electronegative equalization principle to study the affection superconductivity nature for the bond formation in between elements was used.Because of the elements bond formation in superconductors, the Cooper pair electrons origins the bond formation characteristic of the bear superconductivity elements.%库柏电子对是超导电性机制理论中电声子理论的基础.在超导电性理论的研究中占有非常重要的地位.超导材料的种类非常广泛,有单质金属、合金材料、有机化合物、非金属单质、金属与非金属掺杂材料、金属氧化物.因此对不同材料中库柏对电子起源,状态特征的认识,对于全面认识超导电性的特征具有十分重要的意义.在本文中,以电声子机制超导电性理论为基础,用电负性均衡原理研究了元素之间键的形成对超导电性影响的特征,得出了在超导材料中由于元素之间键的形成,库柏对的电子特征具有特殊的性质,库柏对电子的来源取决于承担超导电性的元素之间键的性质特征.这对于全面理解电声子超导理论具有重要意义.对于进一步研究高Tc铜氧化物超导体的超导电性机理具有重要的指导性意义.

  17. The excitation energy spectrum for a system with electron pairs tunneling in a two-leg ladder has a doping depended gap

    CERN Document Server

    Voroshilov, Valentin

    2016-01-01

    A new model with a new Hamiltonian and a new canonical transformation is offered as the means for studying properties of a system of strongly correlated electrons. Consideration of the simplest possible situation, namely a system on non-interacting electrons in a two-leg ladder, leads to an expression for the excitation energy spectrum with no energy gap at the half-filling and with an energy gap away from the half filling.

  18. Pairing instabilities of Dirac composite fermions

    Science.gov (United States)

    Milovanović, M. V.; Ćirić, M. Dimitrijević; Juričić, V.

    2016-09-01

    Recently, a Dirac (particle-hole symmetric) description of composite fermions in the half-filled Landau level (LL) was proposed [D. T. Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027], and we study its possible consequences on BCS (Cooper) pairing of composite fermions (CFs). One of the main consequences is the existence of anisotropic states in single-layer and bilayer systems, which was previously suggested in Jeong and Park [J. S. Jeong and K. Park, Phys. Rev. B 91, 195119 (2015), 10.1103/PhysRevB.91.195119]. We argue that in the half-filled LL in the single-layer case the gapped states may sustain anisotropy, because isotropic pairings may coexist with anisotropic ones. Furthermore, anisotropic pairings with the addition of a particle-hole symmetry-breaking mass term may evolve into rotationally symmetric states, i.e., Pfaffian states of Halperin-Lee-Read (HLR) ordinary CFs. On the basis of the Dirac formalism, we argue that in the quantum Hall bilayer at total filling factor 1, with decreasing distance between the layers, weak pairing of p -wave paired CFs is gradually transformed from Dirac to ordinary, HLR-like, with a concomitant decrease in the CF number. Global characterization of low-energy spectra based on the Dirac CFs agrees well with previous calculations performed by exact diagonalization on a torus. Finally, we discuss features of the Dirac formalism when applied in this context.

  19. Market Competition and Efficient Cooperation

    NARCIS (Netherlands)

    Brandts, J.; Riedl, Arno

    2016-01-01

    We find that in market-partners, market experience has adverse effects on the efficiency of cooperation on both market-winner and market-loser pairs. In market-strangers, pairs of market-winners manage to cooperate more efficiently. These results indicate that it is not market experience per se that

  20. prx-1 functions cooperatively with another paired-related homeobox gene, prx-2, to maintain cell fates within the craniofacial mesenchyme.

    Science.gov (United States)

    Lu, M F; Cheng, H T; Kern, M J; Potter, S S; Tran, B; Diekwisch, T G; Martin, J F

    1999-02-01

    The paired-related homeobox gene, prx-1, is expressed in the postmigratory cranial mesenchyme of all facial prominences and is required for the formation of proximal first arch derivatives. We introduced lacZ into the prx-1 locus to study the developmental fate of cells destined to express prx-1 in the prx-1 mutant background. lacZ was normally expressed in prx-1(neo); prx-1(lacZ )mutant craniofacial mesenchyme up until 11.5 d.p.c. At later time points, lacZ expression was lost from structures that are defective in the prx-1(neo) mutant mice. A related gene, prx-2, demonstrated overlapping expression with prx-1. To test the idea that prx-1 and prx-2 perform redundant functions, we generated prx-1(neo;)prx-2 compound mutant mice. Double mutant mice had novel phenotypes in which the rostral aspect of the mandible was defective, the mandibular incisor arrested as a single, bud-stage tooth germ and Meckel's cartilage was absent. Expression of two markers for tooth development, pax9 and patched, were downregulated. Using a transgene that marks a subset of prx-1-expressing cells in the craniofacial mesenchyme, we showed that cells within the hyoid arch take on the properties of the first branchial arch. These data suggest that prx-1 and prx-2 coordinately regulate gene expression in cells that contribute to the distal aspects of the mandibular arch mesenchyme and that prx-1 and prx-2 play a role in the maintenance of cell fate within the craniofacial mesenchyme.

  1. GAP Analysis Program (GAP)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas GAP Analysis Land Cover database depicts 43 land cover classes for the state of Kansas. The database was generated using a two-stage hybrid classification...

  2. Talent Management: Bridging the Gap

    Science.gov (United States)

    2015-06-12

    Cooper and Colton, you are the greatest gift I could have ever imagined. Daddy’s done with his homework and now we can go to the park–I promise...45 Gap 4: Up-Or-Out Promotions ..................................................................................... 49

  3. Correlation-Enhanced Odd-Parity Interorbital Singlet Pairing in the Iron-Pnictide Superconductor LiFeAs

    Science.gov (United States)

    Nourafkan, R.; Kotliar, G.; Tremblay, A.-M. S.

    2016-09-01

    The rich variety of iron-based superconductors and their complex electronic structure lead to a wide range of possibilities for gap symmetry and pairing components. Here we solve in the two-Fe Brillouin zone the full frequency-dependent linearized Eliashberg equations to investigate spin-fluctuations mediated Cooper pairing for LiFeAs. The magnetic excitations are calculated with the random phase approximation on a correlated electronic structure obtained with density functional theory and dynamical mean field theory. The interaction between electrons through Hund's coupling promotes both the intraorbital dx z (y z ) and the interorbital magnetic susceptibility. As a consequence, the leading pairing channel, conventional s+- , acquires sizable interorbital dx y-dx z (y z ) singlet pairing with odd parity under glide-plane symmetry. The combination of intra- and interorbital components makes the results consistent with available experiments on the angular dependence of the gaps observed on the different Fermi surfaces.

  4. Cooperative Research Paired Trawl Sweep Comparison Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In the spring of 2009, Northeast Fisheries Science Center (NEFSC) replaced the previous standard bottom trawl gear (Yankee 36) with a new standard survey trawl...

  5. Energy gaps in Bi(2)Sr(2)CaCu(2)O(8+δ) cuprate superconductors.

    Science.gov (United States)

    Ren, J K; Zhu, X B; Yu, H F; Tian, Ye; Yang, H F; Gu, C Z; Wang, N L; Ren, Y F; Zhao, S P

    2012-01-01

    The relationship between the cuprate pseudogap (Δ(p)) and superconducting gap (Δ(s)) remains an unsolved mystery. Here, we present a temperature- and doping-dependent tunneling study of submicron Bi(2)Sr(2)CaCu(2)O(8+δ) intrinsic Josephson junctions, which provides a clear evidence that Δ(s) closes at a temperature T(c) (0) well above the superconducting transition temperature T(c) but far below the pseudogap opening temperature T*. We show that the superconducting pairing first occurs predominantly on a limited Fermi surface near the node below T(c) (0), accompanied by a Fermi arc due to the lifetime effects of quasiparticles and Cooper pairs. The arc length has a linear temperature dependence, and as temperature decreases below T(c) it reduces to zero while pairing spreads to the antinodal region of the pseudogap leading to a d-wave superconducting gap on the entire Fermi surface at lower temperatures.

  6. 商务英语毕业设计二人团队合作模式探究%A Study on Pair-Work Cooperation Model in the Gradu-ation Projects for Business English Majors

    Institute of Scientific and Technical Information of China (English)

    王劼华

    2015-01-01

    Many colleges in China have carried out the reform in the forms of graduation projects. Business English Department in Jinling College of Nanjing University has followed this trend, to break the traditional model of"One Project for One Student"and tried a new model of teamwork-based graduation projects. On the basis of the feedback from the questionnaires, the paper studies the feasibility of the pair-work cooperation model, analyzes the problems of the model from the perspective of voluntary teaming, selection of the topic, team communication, and interaction be-tween supervisors and students, raises corresponding solutions and suggestions, and thus proves that this model can be further applied in Business English majors.%国内不少高校开始了毕业设计形式上的改革,南京大学金陵学院商务英语专业也紧跟潮流,打破了传统的一人一题的方式,尝试团队合作完成毕业设计的模式。本论文对二人的团队合作进行了可行性的探讨,根据问卷调查反馈,从自愿组队、合作选题、团队沟通、师生互动等方面分析了这种模式伴随产生的问题,提出了有针对性的对策和建议,并证明了这种新模式值得推广。

  7. The financing of cooperative businesses

    Directory of Open Access Journals (Sweden)

    Alfredo Ispizua

    2005-12-01

    Full Text Available Concern for adequate funding, both at birth and consolidation of the cooperative enterprise, has been, is and will be a constant concern in the cooperative world. So, have emerged in the legal field, a number of financial instruments of various kinds: as equity securities or special interests that seek to cover traditional financing gaps.

  8. Pair programming: more than just working together in pairs.

    Directory of Open Access Journals (Sweden)

    Elsa Mentz

    2012-03-01

    Full Text Available Pair programming originated in the industry where focus is placed on the development of a programme at the most costand time-effective manner, and within the parameters of quality. In this context, a specific programming code is not developed individually; rather, two people work together in order to ensure a higher quality programming code and to motivate each other to work at a faster pace. The problem with this approach was that novice programmers lacked the social skills to work in pairs as they had not been exposed to this sufficiently at tertiary level. The demand of the industry, especially in terms of programmers needing to be able to programme together, led to the incorporation of pair programming at tertiary level in the late nineties. The pedagogical principles on which any teaching-learning strategy should be built were, however, largely overlooked during this process. This article firstly looks into the semantic and ontological differences between co-operative and collaborative learning and secondly argues that pair programming, within the context of a social constructivist approach to teaching and learning, can be seen as a co-operative teaching-learning strategy. Pair programming is more than just allowing two students to work together on a programming task. The more structured way, in which pair programming needs to be implemented, concur with the principles of co-operative learning. The article concludes that the correct pedagogical application of pair programming as a co-operative teaching-learning strategy in tertiary education will result in improved learning capital.

  9. Orbital-Parity Selective Superconducting Pairing Structures of Fe-based Superconductors under Glide Symmetry

    Science.gov (United States)

    Lin, Chiahui; Chou, Chung-Pin; Yin, Wei-Guo; Ku, Wei

    2014-03-01

    We show that the superconductivity in Fe-based superconductors consists of zero and finite momentum (π , π , 0) Cooper pairs with the same and different parities of the Fe 3 d orbitals respectively. The former develops the distinct gap structures for each orbital parity, and the latter is characteristic of spin singlet, spacial oddness and time reversal symmetry breaking. This originates from the unit cell containing two Fe atoms and two anions of staggered positioning with respect to the Fe square lattice. The in-plane translation is turned into glide translation, which dictates orbital-parity selective quasiparticles. Such novel pairing structures explain the unusual gap angular modulation on the hole pockets in recent ARPES and STS experiments. Work supported by DOE DE-AC02-98CH10886 and Chinese Academy of Engineering Physics and Ministry of Science and Technology.

  10. Tunable sub-gap radiation detection with superconducting resonators

    Science.gov (United States)

    Dupré, O.; Benoît, A.; Calvo, M.; Catalano, A.; Goupy, J.; Hoarau, C.; Klein, T.; Le Calvez, K.; Sacépé, B.; Monfardini, A.; Levy-Bertrand, F.

    2017-04-01

    We have fabricated planar amorphous indium oxide superconducting resonators ({T}{{c}}∼ 2.8 K) that are sensitive to frequency-selective radiation in the range of 7–10 GHz. Those values lay far below twice the superconducting gap that is worth about 200 GHz. The photon detection consists in a shift of the fundamental resonance frequency. We show that the detected frequency can be adjusted by modulating the total length of the superconducting resonator. We attribute those observations to the excitation of higher-order resonance modes. The coupling between the fundamental lumped and the higher order distributed resonance is due to the kinetic inductance nonlinearity with current. These devices, that we have called sub-gap kinetic inductance detectors, are to be distinguished from the standard kinetic inductance detectors in which quasi-particles are generated when incident light breaks down Cooper pairs.

  11. Pairing in a dry Fermi sea.

    Science.gov (United States)

    Maier, T A; Staar, P; Mishra, V; Chatterjee, U; Campuzano, J C; Scalapino, D J

    2016-06-17

    In the traditional Bardeen-Cooper-Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and -k has a log singularity as the temperature decreases. This so-called Cooper instability arises from the presence of an electron Fermi sea. It means that an attractive interaction, no matter how weak, will eventually lead to a pairing instability. However, in the pseudogap regime of the cuprate superconductors, where parts of the Fermi surface are destroyed, this log singularity is suppressed, raising the question of how pairing occurs in the absence of a Fermi sea. Here we report Hubbard model numerical results and the analysis of angular-resolved photoemission experiments on a cuprate superconductor. In contrast to the traditional theory, we find that in the pseudogap regime the pairing instability arises from an increase in the strength of the spin-fluctuation pairing interaction as the temperature decreases rather than the Cooper log instability.

  12. Observation of Momentum-Confined In-Gap Impurity State in Ba_{0.6}K_{0.4}Fe_{2}As_{2}: Evidence for Antiphase s_{±} Pairing

    Directory of Open Access Journals (Sweden)

    P. Zhang

    2014-07-01

    Full Text Available We report the observation by angle-resolved photoemission spectroscopy of an impurity state located inside the superconducting gap of Ba_{0.6}K_{0.4}Fe_{2}As_{2} and vanishing above the superconducting critical temperature, for which the spectral weight is confined in momentum space near the Fermi wave-vector positions. We demonstrate, supported by theoretical simulations, that this in-gap state originates from weak scattering between bands with opposite sign of the superconducting-gap phase. This weak scattering, likely due to off-plane nonmagnetic (Ba, K disorder, occurs mostly among neighboring Fermi surfaces, suggesting that the superconducting-gap phase changes sign within holelike (and electronlike bands. Our results impose severe restrictions on the models promoted to explain high-temperature superconductivity in these materials.

  13. Pairing correlations in exotic nuclei

    CERN Document Server

    Sagawa, H

    2012-01-01

    The BCS and HFB theories which can accommodate the pairing correlations in the ground states of atomic nuclei are presented. As an application of the pairing theories, we investigate the spatial extension of weakly bound Ne and C isotopes by taking into account the pairing correlation with the Hartree-Fock-Bogoliubov (HFB) method and a 3-body model, respectively. We show that the odd-even staggering in the reaction cross sections of $^{30,31,32}$Ne and $^{14,15,16}$C are successfully reproduced, and thus the staggering can be attributed to the unique role of pairing correlations in nuclei far from the stability line. A correlation between a one-neutron separation energy and the anti-halo effect is demonstrated for $s$- and p-waves using the HFB wave functions. We also propose effective density-dependent pairing interactions which reproduce both the neutron-neutron ($nn$) scattering length at zero density and the neutron pairing gap in uniform matter. Then, we apply these interactions to study pairing gaps in ...

  14. Spin-triplet paired state induced by Hund's rule coupling and correlations: a fully statistically consistent Gutzwiller approach.

    Science.gov (United States)

    Spałek, J; Zegrodnik, M

    2013-10-30

    The intrasite and intersite spin-triplet pairing gaps induced by interband Hund's rule coupling and their correlations are analyzed in the doubly degenerate Hubbard Hamiltonian. To include the effect of correlations, the statistically consistent Gutzwiller approximation is used. In this approach the consistency means that the averages calculated from the self-consistent equations and those determined variationally coincide with each other. Emphasis is put on the solution for which the average particle number is conserved when carrying out the Gutzwiller projection. This method leads to a stable equal-spin paired state in the so-called repulsive interactions limit (U > 3J) in the regime of moderate correlations. The interband hybridization introduces an inequivalence of the bands which, above a critical magnitude, suppresses the paired state due to both the Fermi-wavevector mismatch for the Cooper pair and the interband hopping allowed by the Pauli principle.

  15. Direct evidence for a magnetic f-electron-mediated pairing mechanism of heavy-fermion superconductivity in CeCoIn5.

    Science.gov (United States)

    Van Dyke, John S; Massee, Freek; Allan, Milan P; Davis, J C Séamus; Petrovic, Cedomir; Morr, Dirk K

    2014-08-12

    To identify the microscopic mechanism of heavy-fermion Cooper pairing is an unresolved challenge in quantum matter studies; it may also relate closely to finding the pairing mechanism of high-temperature superconductivity. Magnetically mediated Cooper pairing has long been the conjectured basis of heavy-fermion superconductivity but no direct verification of this hypothesis was achievable. Here, we use a novel approach based on precision measurements of the heavy-fermion band structure using quasiparticle interference imaging to reveal quantitatively the momentum space (k-space) structure of the f-electron magnetic interactions of CeCoIn5. Then, by solving the superconducting gap equations on the two heavy-fermion bands Ek(α,β) with these magnetic interactions as mediators of the Cooper pairing, we derive a series of quantitative predictions about the superconductive state. The agreement found between these diverse predictions and the measured characteristics of superconducting CeCoIn5 then provides direct evidence that the heavy-fermion Cooper pairing is indeed mediated by f-electron magnetism.

  16. Conflictual cooperation

    DEFF Research Database (Denmark)

    Axel, Erik

    2011-01-01

    , cooperation appeared as the continuous reworking of contradictions in the local arrangement of societal con- ditions. Subjects were distributed and distributed themselves according to social privileges, resources, and dilemmas in cooperation. Here, the subjects’ activities and understandings took form from...

  17. Knowledge Gaps

    DEFF Research Database (Denmark)

    Lyles, Marjorie; Pedersen, Torben; Petersen, Bent

    2003-01-01

    The study explores what factors influence the reduction of managers' perceivedknowledge gaps in the context of the environments of foreign markets. Potentialdeterminants are derived from traditional internationalization theory as well asorganizational learning theory, including the concept......, assimilating, and utilizing knowledge - are crucial determinants ofknowledge gap elimination. In contrast, the two factors deemed essential in traditionalinternationalization process theory - elapsed time of operations and experientiallearning - are found to have no or limited effect.Key words......: Internationalization, knowledge gap, absorptive capacity, learning box....

  18. Cooperative Learning

    Institute of Scientific and Technical Information of China (English)

    桑莹莹

    2015-01-01

    This paper is about the cooperative learning as a teaching method in a second language learning class. It mainly talks about the background, foundation, features, definitions, components, goals, advantages and disadvantages of cooperative learning. And as the encounter of the disadvantages in cooperative learning, this paper also proposes some strategies.

  19. Ensemble treatments of thermal pairing in nuclei

    Science.gov (United States)

    Hung, Nguyen Quang; Dang, Nguyen Dinh

    2009-10-01

    A systematic comparison is conducted for pairing properties of finite systems at nonzero temperature as predicted by the exact solutions of the pairing problem embedded in three principal statistical ensembles, namely the grandcanonical ensemble, canonical ensemble and microcanonical ensemble, as well as the unprojected (FTBCS1+SCQRPA) and Lipkin-Nogami projected (FTLN1+SCQRPA) theories that include the quasiparticle number fluctuation and coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The numerical calculations are performed for the pairing gap, total energy, heat capacity, entropy, and microcanonical temperature within the doubly-folded equidistant multilevel pairing model. The FTLN1+SCQRPA predictions are found to agree best with the exact grand-canonical results. In general, all approaches clearly show that the superfluid-normal phase transition is smoothed out in finite systems. A novel formula is suggested for extracting the empirical pairing gap in reasonable agreement with the exact canonical results.

  20. Charge Aspects of Composite Pair Superconductivity

    Science.gov (United States)

    Flint, Rebecca

    2014-03-01

    Conventional Cooper pairs form from well-defined electronic quasiparticles, making the internal structure of the pair irrelevant. However, in the 115 family of superconductors, the heavy electrons are forming as they pair and the internal pair structure becomes as important as the pairing mechanism. Conventional spin fluctuation mediated pairing cannot capture the direct transition from incoherent local moments to heavy fermion superconductivity, but the formation of composite pairs favored by the two channel Kondo effect can. These composite pairs are local d-wave pairs formed by two conduction electrons in orthogonal Kondo channels screening the same local moment. Composite pairing shares the same symmetries as magnetically mediated pairing, however, only composite pairing necessarily involves a redistribution of charge within the unit cell originating from the internal pair structure, both as a monopole (valence change) and a quadrupole effect. This redistribution will onset sharply at the superconducting transition temperature. A smoking gun test for composite pairing is therefore a sharp signature at Tc - for example, a cusp in the Mossbauer isomer shift in NpPd5Al2 or in the NQR shift in (Ce,Pu)CoIn5.

  1. Pairing versus quarteting coherence length

    CERN Document Server

    Delion, Doru S

    2015-01-01

    We systematically analyse the coherence length in even-even nuclei. The pairing coherence length in the spin-singlet channel for the effective density dependent delta (DDD) and Gaussian interaction is estimated. We consider in our calculations bound states as well as narrow resonances. It turns out that the pairing gaps given by the DDD interaction are similar to those of the Gaussian potential if one renormalizes the radial width to the nuclear radius. The correlations induced by the pairing interaction have in all considered cases a long range character inside the nucleus and decrease towards the surface. The mean coherence length is larger than the geometrical radius for light nuclei and approaches this value for heavy nuclei. The effect of the temperature and states in continuum is investigated. Strong shell effects are evidenced, especially for protons. We generalize this concept to quartets by considering similar relations, but between proton and neutron pairs. The quartet coherence length has a similar...

  2. Gap Junctions

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  3. Gap junctions.

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2012-07-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1853-1872, 2012.

  4. Superconductivity: The persistence of pairs

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, Alex; Littlewood, Peter

    2015-05-20

    Superconductivity stems from a weak attraction between electrons that causes them to form bound pairs and behave much like bosons. These so-called Cooper pairs are phase coherent, which leads to the astonishing properties of zero electrical resistance and magnetic flux expulsion typical of superconducting materials. This coherent state may be qualitatively understood within the Bose–Einstein condensate (BEC) model, which predicts that a gas of interacting bosons will become unstable below a critical temperature and condense into a phase of matter with a macroscopic, coherent population in the lowest energy state, as happens in 4He or cold atomic gases. The successful theory proposed by Bardeen, Cooper and Schrieffer (BCS) predicts that at the superconducting transition temperature Tc, electrons simultaneously form pairs and condense, with no sign of pairing above Tc. Theorists have long surmised that the BCS and BEC models are opposite limits of a single theory and that strong interactions or low density can, in principle, drive the system to a paired state at a temperature Tpair higher than Tc, making the transition to the superconducting state BEC-like (Fig. 1). Yet most superconductors to date are reasonably well described by BCS theory or its extensions, and there has been scant evidence in electronic materials for the existence of pairing independent of the full superconducting state (though an active debate rages over the cuprate superconductors). Writing in Nature, Jeremy Levy and colleagues have now used ingenious nanostructured devices to provide evidence for electron pairing1. Perhaps surprisingly, the material they have studied is a venerable, yet enigmatic, low-temperature superconductor, SrTiO3.

  5. Mythic gaps

    Directory of Open Access Journals (Sweden)

    William Hansen

    2014-11-01

    Full Text Available Different kinds of omissions sometimes occur, or are perceived to occur, in traditional narratives and in tradition-inspired literature. A familiar instance is when a narrator realizes that he or she does not fully remember the story that he or she has begun to tell, and so leaves out part of it, which for listeners may possibly result in an unintelligible narrative. But many instances of narrative gap are not so obvious. From straightforward, objective gaps one can distinguish less-obvious subjective gaps: in many cases narrators do not leave out anything crucial or truly relevant from their exposition, and yet readers perceive gaps and take steps to fill them. The present paper considers four examples of subjective gaps drawn from ancient Greek literature (the Pandora myth, ancient Roman literature (the Pygmalion legend, ancient Hebrew literature (the Joseph legend, and early Christian literature (the Jesus legend. I consider the quite varied ways in which interpreters expand the inherited texts of these stories, such as by devising names, manufacturing motives, creating backstories, and in general filling in biographical ellipses. Finally, I suggest an explanation for the phenomenon of subjective gaps, arguing that, despite their variety, they have a single cause.

  6. GAP Analysis Program (GAP) Raster

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas GAP Land Cover database depicts 43 land cover classes for the state of Kansas. The database was generated using a two-stage hybrid classification of...

  7. Pairing Learners in Pair Work Activity

    Science.gov (United States)

    Storch, Neomy; Aldosari, Ali

    2013-01-01

    Although pair work is advocated by major theories of second language (L2) learning and research findings suggest that pair work facilitates L2 learning, what is unclear is how to best pair students in L2 classes of mixed L2 proficiency. This study investigated the nature of pair work in an English as a Foreign Language (EFL) class in a college in…

  8. Triplet Pairing in Neutron Matter

    CERN Document Server

    Khodel, V V; Clark, J W

    2001-01-01

    The separation method developed earlier by us [Nucl. Phys. {\\bf A598} 390 (1996)] to calculate and analyze solutions of the BCS gap equation for $^1$S$_0$ pairing is extended and applied to $^3$P$_2$--$^3$F$_2$ pairing in pure neutron matter. The pairing matrix elements are written as a separable part plus a remainder that vanishes when either momentum variable is on the Fermi surface. This decomposition effects a separation of the problem of determining the dependence of the gap components in a spin-angle representation on the magnitude of the momentum (described by a set of functions independent of magnetic quantum number) from the problem of determining the dependence of the gap on angle or magnetic projection. The former problem is solved through a set of nonsingular, quasilinear integral equations, providing inputs for solution of the latter problem through a coupled system of algebraic equations for a set of numerical coefficients. An incisive criterion is given for finding the upper critical density fo...

  9. Knowledge Gaps

    DEFF Research Database (Denmark)

    Lyles, Marjorie; Pedersen, Torben; Petersen, Bent

    2003-01-01

    of absorptive capacity. Building onthese literature streams a conceptual model is developed and tested on a set of primarydata of Danish firms and their foreign market operations. The empirical study suggeststhat the factors that pertain to the absorptive capacity concept - capabilities ofrecognizing......, assimilating, and utilizing knowledge - are crucial determinants ofknowledge gap elimination. In contrast, the two factors deemed essential in traditionalinternationalization process theory - elapsed time of operations and experientiallearning - are found to have no or limited effect.Key words......: Internationalization, knowledge gap, absorptive capacity, learning box....

  10. The origin of multiple superconducting gaps in MgB2.

    Science.gov (United States)

    Souma, S; Machida, Y; Sato, T; Takahashi, T; Matsui, H; Wang, S-C; Ding, H; Kaminski, A; Campuzano, J C; Sasaki, S; Kadowaki, K

    2003-05-01

    Magnesium diboride, MgB2, has the highest transition temperature (T(c) = 39 K) of the known metallic superconductors. Whether the anomalously high T(c) can be described within the conventional BCS (Bardeen-Cooper-Schrieffer) framework has been debated. The key to understanding superconductivity lies with the 'superconducting energy gap' associated with the formation of the superconducting pairs. Recently, the existence of two kinds of superconducting gaps in MgB2 has been suggested by several experiments; this is in contrast to both conventional and high-T(c) superconductors. A clear demonstration of two gaps has not yet been made because the previous experiments lacked the ability to resolve the momentum of the superconducting electrons. Here we report direct experimental evidence for the two-band superconductivity in MgB2, by separately observing the superconducting gaps of the sigma and pi bands (as well as a surface band). The gaps have distinctly different sizes, which unambiguously establishes MgB2 as a two-gap superconductor.

  11. Concealed d-wave pairs in the s± condensate of iron-based superconductors.

    Science.gov (United States)

    Ong, Tzen; Coleman, Piers; Schmalian, Jörg

    2016-05-17

    A central question in iron-based superconductivity is the mechanism by which the paired electrons minimize their strong mutual Coulomb repulsion. In most unconventional superconductors, Coulomb repulsion is minimized through the formation of higher angular momentum Cooper pairs, with Fermi surface nodes in the pair wavefunction. The apparent absence of such nodes in the iron-based superconductors has led to a belief they form an s-wave ([Formula: see text]) singlet state, which changes sign between the electron and hole pockets. However, the multiorbital nature of these systems opens an alternative possibility. Here, we propose a new class of [Formula: see text] state containing a condensate of d-wave Cooper pairs, concealed by their entanglement with the iron orbitals. By combining the d-wave ([Formula: see text]) motion of the pairs with the internal angular momenta [Formula: see text] of the iron orbitals to make a singlet ([Formula: see text]), an [Formula: see text] superconductor with a nontrivial topology is formed. This scenario allows us to understand the development of octet nodes in potassium-doped Ba1-x KXFe2As2 as a reconfiguration of the orbital and internal angular momentum into a high spin ([Formula: see text]) state; the reverse transition under pressure into a fully gapped state can then be interpreted as a return to the low-spin singlet. The formation of orbitally entangled pairs is predicted to give rise to a shift in the orbital content at the Fermi surface, which can be tested via laser-based angle-resolved photoemission spectroscopy.

  12. Grouping and Achievement in Cooperative Learning

    Science.gov (United States)

    Baer, John

    2003-01-01

    Colleges typically group students homogeneously in classes by means of both admission requirements and course prerequisites, but when professors form cooperative learning groups within classes they generally use heterogeneous grouping. Authors compared heterogeneously and homogeneously grouped cooperative learning groups in six paired classes,…

  13. Topologically stable gapped state in a layered superconductor

    Science.gov (United States)

    Doria, Mauro; Cariglia, Marco; Vargas-Paredes, Alfredo A.

    2014-03-01

    We show that a layered charged superconductor, described by a spinorial (two-component) order parameter, has a gapped state above the ground state, topologically protected from decay. This state is made of skyrmions, breaks the time reversal symmetry and produces a weak local magnetic field. This excited but stable state contains spontaneous circulating supercurrents, with flow and counter flow in the layers, even without the presence of an external magnetic field. We derive the order parameter and the local magnetic field of this skyrmion state from the Abrikosov-Bogomolny (first order) equations, instead of the second order variational equations. We find a gap density of the order of 0 . 1hmaxmeV.nm-3 , where hmax is the maximum local magnetic field between layers expressed in Gauss. The present threshold of detection, set by μSR and NMR/NQR, hmax ~ 0 . 01G , gives a gap density of the order 10-3meV.nm-3 for the single-layer cuprates (inter-layer distance d ~ 1 . 0 nm). We suggest that the pseudogap is a skyrmion state, and so, estimate that the density of carriers that condense in the pseudogap is of the order of 10-4nm-3 , or 0 . 01 % of the Cooper pair density in the cuprates. Acknowledge support from CNPq-Brazil.

  14. GAP Analysis Bulletin Number 15

    Science.gov (United States)

    Maxwell, Jill; Gergely, Kevin; Aycrigg, Jocelyn; Canonico, Gabrielle; Davidson, Anne; Coffey, Nicole

    2008-01-01

    The Mission of the Gap Analysis Program (GAP) is to promote conservation by providing broad geographic information on biological diversity to resource managers, planners, and policy makers who can use the information to make informed decisions. As part of the National Biological Information Infrastructure (NBII) ?a collaborative program to provide increased access to data and information on the nation?s biological resources--GAP data and analytical tools have been used in hundreds of applications: from basic research to comprehensive state wildlife plans; from educational projects in schools to ecoregional assessments of biodiversity. The challenge: keeping common species common means protecting them BEFORE they become threatened. To do this on a state or regional basis requires key information such as land cover descriptions, predicted distribution maps for native animals, and an assessment of the level of protection currently given to those plants and animals. GAP works cooperatively with Federal, state, and local natural resource professionals and academics to provide this kind of information. GAP activities focus on the creation of state and regional databases and maps that depict patterns of land management, land cover, and biodiversity. These data can be used to identify ?gaps? in conservation--instances where an animal or plant community is not adequately represented on the existing network of conservation lands. GAP is administered through the U.S. Geological Survey. Through building partnerships among disparate groups, GAP hopes to foster the kind of collaboration that is needed to address conservation issues on a broad scale. For more information, contact: John Mosesso National GAP Director 703-648-4079 Kevin Gergely National GAP Operations Manager 208-885-3565

  15. Cooperative Dyads: Impact on Text Learning and Transfer.

    Science.gov (United States)

    McDonald, Barbara A.; And Others

    1985-01-01

    In two experiments, college student pairs who were given a systematic strategy for learning cooperatively from a text were compared with pairs who created their own strategies and with individuals who used the systematic or their own strategy. The cooperative learning strategy facilitated both initial learning and transfer. (Author/GDC)

  16. ENHANCING COOPERATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    China and Japan can cooperate on a wide scope of issues, such as the organization of the Beijing Olympic Games next year and aid to Africa,said Ide Keiji, Minister of Public Relations, Press, Culture, Education and Sports and Spokesperson of the Embassy

  17. Powered Tate Pairing Computation

    Science.gov (United States)

    Kang, Bo Gyeong; Park, Je Hong

    In this letter, we provide a simple proof of bilinearity for the eta pairing. Based on it, we show an efficient method to compute the powered Tate pairing as well. Although efficiency of our method is equivalent to that of the Tate pairing on the eta pairing approach, but ours is more general in principle.

  18. Pairings on hyperelliptic curves

    CERN Document Server

    Balakrishnan, Jennifer; Chisholm, Sarah; Eisentraeger, Kirsten; Stange, Katherine; Teske, Edlyn

    2009-01-01

    We assemble and reorganize the recent work in the area of hyperelliptic pairings: We survey the research on constructing hyperelliptic curves suitable for pairing-based cryptography. We also showcase the hyperelliptic pairings proposed to date, and develop a unifying framework. We discuss the techniques used to optimize the pairing computation on hyperelliptic curves, and present many directions for further research.

  19. Pairing in the BCS and LN approximations using continuum single particle level density

    Science.gov (United States)

    Id Betan, R. M.; Repetto, C. E.

    2017-04-01

    Understanding the properties of drip line nuclei requires to take into account the correlations with the continuum spectrum of energy of the system. This paper has the purpose to show that the continuum single particle level density is a convenient way to consider the pairing correlation in the continuum. Isospin mean-field and isospin pairing strength are used to find the Bardeen-Cooper-Schrieffer (BCS) and Lipkin-Nogami (LN) approximate solutions of the pairing Hamiltonian. Several physical properties of the whole chain of the Tin isotope, as gap parameter, Fermi level, binding energy, and one- and two-neutron separation energies, were calculated and compared with other methods and with experimental data when they exist. It is shown that the use of the continuum single particle level density is an economical way to include explicitly the correlations with the continuum spectrum of energy in large scale mass calculation. It is also shown that the computed properties are in good agreement with experimental data and with more sophisticated treatment of the pairing interaction.

  20. Pure Pairing Modes in Trapped Fermion Systems

    Science.gov (United States)

    Capuzzi, P.; Hernández, E. S.; Szybisz, L.

    2013-05-01

    We present numerical predictions for the shape of the pairing fluctuations in harmonically trapped atomic 6Li with two spin projections, based on the fluiddynamical description of cold fermions with pairing interactions. In previous works it has been shown that when the equilibrium of a symmetric mixture is perturbed, the linearized fluiddynamic equations decouple into two sets, one containing the sound mode of fermion superfluids and the other the pairing mode. The latter corresponds to oscillations of the modulus of the complex gap and is driven by the kinetic energy densities of the particles and of the pairs. Assuming proportionality between the heat flux and the energy gradient, the particle kinetic energy undergoes a diffusive behavior and the diffusion parameter is the key parameter for the relaxation time scale. We examine a possible range of values for this parameter and find that the shape of the pairing oscillation is rather insensitive to the precise value of the transport coefficient. Moreover, the pairing fluctuation is largely confined to the center of the trap, and the energy of the pairing mode is consistent with the magnitude of the equilibrium gap.

  1. Pairing phase transition and thermodynamical quantities in 148,149Sm

    Science.gov (United States)

    Razavi, R.; Behkami, A. N.; Dehghani, V.

    2014-10-01

    The nuclear level densities and entropies in 148,149Sm have been calculated in the framework of the superconducting theory that includes modified nuclear pairing gap. For modified pairing gap parameter the smooth transition from the BCS to the Fermi type distributions is used. By applying modified pairing gap, the extracted S-shaped heat capacity as a function of nuclear temperature exhibits a physical and smoother behavior instead of the singular behavior predicted by the BCS equations at critical temperature.

  2. Pairing phase transition and thermodynamical quantities in {sup 148,149}Sm

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, R., E-mail: rrazavin@ihu.ac.ir [Department of Physics, Faculty of Science, Imam Hossein Comprehensive University, Tehran (Iran, Islamic Republic of); Behkami, A.N. [Fars Science and Research Center, Islamic Azad University, Shiraz (Iran, Islamic Republic of); Dehghani, V. [Physics Department, Faculty of Science, University of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of)

    2014-10-15

    The nuclear level densities and entropies in {sup 148,149}Sm have been calculated in the framework of the superconducting theory that includes modified nuclear pairing gap. For modified pairing gap parameter the smooth transition from the BCS to the Fermi type distributions is used. By applying modified pairing gap, the extracted S-shaped heat capacity as a function of nuclear temperature exhibits a physical and smoother behavior instead of the singular behavior predicted by the BCS equations at critical temperature.

  3. Casimir light: photon pairs.

    OpenAIRE

    1993-01-01

    Expressions are developed for weak single pair emission probability and strong emission average number of pairs. The water transparency cutoff is closely realized, showing that the fundamental time scale is even shorter.

  4. A stabilized pairing functional

    CERN Document Server

    Erler, J; Reinhard, P --G

    2008-01-01

    We propose a modified pairing functional for nuclear structure calculations which avoids the abrupt phase transition between pairing and non-pairing states. The intended application is the description of nuclear collective motion where the smoothing of the transition is compulsory to remove singularities. The stabilized pairing functional allows a thoroughly variational formulation, unlike the Lipkin-Nogami (LN) scheme which is often used for the purpose of smoothing. First applications to nuclear ground states and collective excitations prove the reliability and efficiency of the proposed stabilized pairing.

  5. Quantum Cooperation of Insects

    CERN Document Server

    Summhammer, J

    2005-01-01

    We investigate the cooperation of two insects who share a large number of maximally entangled EPR-pairs to help them decide whether to execute certain actions. In the first example, two ants must push a pebble, which may be too heavy for one ant. In the second example, two distant butterflies must find each other. In both examples the individuals make classical random choices of possible directions, followed by a quantum decision whether to move or to wait. This combination reflects scarce environmental information and the small brain's limited capacity for complex analysis. With quantum mechanical entanglement the two ants can push the pebble up to twice as far as uncorrelated ants, and the two butterflies need only between 48% and 83% of the classical flight path to find each other.

  6. Learning to Teach as Situated Learning: An Examination of Student Teachers as Legitimate Peripheral Participants in Cooperating Teachers' Classrooms

    Science.gov (United States)

    McDonald, Eric J.

    Learning to teach science well is a complex endeavor and student teaching provides a time for emerging teachers to learn how to reason in this uncertain landscape. Many pre-service teachers have rated student teaching as a very important part of their teacher education program (Koerner, Rust, & Baumgartner, 2002; Levine, 2006) and there is little doubt that this aspect of teacher preparation has a great impact (Wilson, Floden, Ferrinin-Mundy, 2001). It is surprising, therefore, that the interaction between the cooperating teacher and student teacher represents a gap in the literature (Cochran-Smith & Zeichner, 2005). In fact, little effort has been made in science education "to understand the contributions of cooperating teachers and teacher educators" (p. 322). Research is needed into not only how teacher preparation programs can help pre-service teachers make this transition from student teacher to effective teacher but also how the expertise of the cooperating teacher can be a better articulated part of the development of the student teacher. This instrumental case study examines the nature and substance of the cooperating teacher/student teacher conversations and the changes in those conversations over time. Using the theoretical framework of situated learning (Lave & Wenger, 1991; Lave, 1996) the movement of the student teacher from their position on the periphery of practice toward a more central role is examined. Three cooperating teacher/student teacher pairs provided insight into this important time with case data coming from pre and post interviews, baseline surveys, weekly update surveys, and recorded conversations from the pair during their time together. Four major themes emerged from the cases and from cross case comparisons with implications for student teachers regarding how they react to greater responsibility, cooperating teachers regarding how they give access to the community of practice, and the teacher preparation community regarding the role

  7. Optimal Relay Assignment and Power Allocation for Cooperative Communications

    Institute of Scientific and Technical Information of China (English)

    Kun Xie; Jian-Nong Cao; Ji-Gang Wen

    2013-01-01

    Cooperative communication for wireless networks has gained a lot of recent interest due to its ability to mitigate fading with exploration of spatial diversity.In this paper,we study a joint optimization problem of jointly considering transmission mode selection,relay assignment and power allocation to maximize the capacity of the network through cooperative wireless communications.This problem is much more challenging than relay assignment considered in literature work which simply targets to maximize the transmission capacity for a single transmission pair.We formulate the problem as a variation of the maximum weight matching problem where the weight is a function over power values which must meet power constraints (VMWMC).Although VMWMC is a non-convex problem whose complexity increases exponentially with the number of relay nodes,we show that the duality gap of VMWMC is virtual zero.Based on this result,we propose a solution using Lagrange dual decomposition to reduce the computation complexity.We do simulations to evaluate the performance of the proposed solution.The results show that our solution can achieve maximum network capacity with much less computation time compared with exhaustive search,and our solution outperforms existing sub-optimal solutions that can only achieve much lower network capacity.

  8. Fostering cooperative activism through critical design

    DEFF Research Database (Denmark)

    Menendez Blanco, Maria; Bjørn, Pernille; De Angeli, Antonella

    2017-01-01

    Critical design is gaining momentum in interaction design, yet little CSCW research has focused on articulating the cooperative potentials of critical design artefacts. We address this gap by reflecting upon a design project aimed at overturning the prevailing narrative regarding dyslexia in Italy....... The adversarial propositions embedded in our critical design artefacts challenged the description of dyslexia as a learning disorder putting forward the view of a learning difference. These artefacts demonstrated their capacity to bridge heterogeneous social worlds (those of teachers, children, and parents......) into one cooperative entity and mobilise cooperative activism. The contribution to CSCW is two-fold. Firstly, we introduce the cooperative potentials of critical design artefacts; secondly, we propose critical design as a strategy for researchers engaging with cooperative activism....

  9. International nuclear cooperation in Asia

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Yong-Kyu

    1987-01-01

    Nuclear power project traditionally involve huge financial investment, highly sophisticated technology, and long lead time. Many countries, particularly developing ones, find it impossible to implement their nuclear power programs without technical cooperation and assistance from advanced countries. In this Asia and Pacific Region, seven countries have commercial nuclear power units in operation and/or under construction. Korea has six nuclear power units in operation, and three under construction. Active nuclear cooperation has been instrumental in implementing her abmitious nuclear power programs successfully. Nuclear cooperation is one of the widely recognized necessities, which is quite often talked about among the countries of the Asia and Pacific Region. But the differences in nuclear maturity and national interests among those in the region seem to be standing against it. Given the constraints, it is not easy to select appropriate areas for cooperation. There is no doubt, however, that they should include the nuclear policy, nuclear safety, radwaste management, radiological protection, and the management of nuclear units. In order to effectively promote nuclear cooperation in the Region, the scope of RCA activities must be expanded to include the nuclear power area. The Regional Nuclear Data Bank, the Regional Training Center and the Nuclear Emergency Response Center, for example, would be the effective tools for cooperation to meet the demands of the countries in the Region. In view of the technological gap between Japan and all others in the region, we cannot speak of a regional nuclear cooperation without heavily counting on Japan, the most advanced nuclear state in the region. For these reasons, Japan is expected to share an increasing portion of her nuclear technology with others.

  10. Pairing properties of realistic effective interactions

    Directory of Open Access Journals (Sweden)

    Gargano A.

    2016-01-01

    Full Text Available We investigate the pairing properties of an effective shell-model interaction defined within a model space outside 132Sn and derived by means of perturbation theory from the CD-Bonn free nucleon-nucleon potential. It turns out that the neutron pairing component of the effective interaction is significantly weaker than the proton one, which accounts for the large pairing gap difference observed in the two-valence identical particle nuclei 134Sn and 134Te. The role of the contribution arising from one particle-one hole excitations in determining the pairing force is discussed and its microscopic structure is also analyzed in terms of the multipole decomposition.

  11. Superconducting gap anomaly in heavy fermion systems

    Indian Academy of Sciences (India)

    G C Rout; M S Ojha; S N Behera

    2008-04-01

    The heavy fermion system (HFS) is described by the periodic Anderson model (PAM), treating the Coulomb correlation between the -electrons in the mean-field Hartree-Fock approximation. Superconductivity is introduced by a BCS-type pairing term among the conduction electrons. Within this approximation the equation for the superconducting gap is derived, which depends on the effective position of the energy level of the -electrons relative to the Fermi level. The latter in turn depends on the occupation probability f of the -electrons. The gap equation is solved self-consistently with the equation for f; and their temperature dependences are studied for different positions of the bare -electron energy level, with respect to the Fermi level. The dependence of the superconducting gap on the hybridization leads to a re-entrant behaviour with increasing strength. The induced pairing between the -electrons and the pairing of mixed conduction and -electrons due to hybridization are also determined. The temperature dependence of the hybridization parameter, which characterizes the number of electrons with mixed character and represents the number of heavy electrons is studied. This number is shown to be small. The quasi-particle density of states (DOS) shows the existence of a pseudo-gap due to superconductivity and the signature of a hybridization gap at the Fermi level. For the choice of the model parameters, the DOS shows that the HFS is a metal and undergoes a transition to the gap-less superconducting state.

  12. Theoretical study of pair density wave superconductors

    Science.gov (United States)

    Zheng, Zhichao

    In conventional superconductors, the Cooper pairs are formed from quasiparticles. We explore another type of superconducting state, a pair density wave (PDW) order, which spontaneously breaks some of the translational and point group symmetries. In a PDW superconductor, the order parameter is a periodic function of the center-of-mass coordinate, and the spatial average value of the superconducting order parameter vanishes. In the early 1960s, following the success of the BCS theory of superconductivity, Fulde and Ferrell and Larkin and Ovchinnikov (FFLO) developed theories of inhomogeneous superconducting states. Because of this Zeeman splitting in a magnetic field, the Cooper pairs having a nonzero center-of-mass momentum are more stable than the normal pairing, leading to the FFLO state. Experiments suggest possible occurrence of the FFLO state in the heavy-fermion compound CeCoIn5, and in quasi-low-dimensional organic superconductors. FFLO phases have also been argued to be of importance in understanding ultracold atomic Fermi gases and in the formation of color superconductivity in high density quark matter. In all Fermi superfluids known at the present time, Cooper pairs are composed of particles with spin 1/2. The spin component of a pair wave function can be characterized by its total spin S = 0 (singlet) and S = 1 (triplet). In the discovered broken inversion superconductors CePt3Si, Li2Pt3B, and Li2Pd3B, the magnetic field leads to novel inhomogeneous superconducting states, namely the helical phase and the multiple-q phase. Its order parameter exhibits periodicity similar to FFLO phase, and the consequences of both phases are same: the enhancement of transition temperature as a function of magnetic field. We have studied the PDW phases in broken parity superconductors with vortices included. By studying PDW vortex states, we find the usual Abrikosov vortex solution is unstable against a new solution with fractional vortex pairs. We have also studied the

  13. Observation of a pairing pseudogap in a two-dimensional Fermi gas.

    Science.gov (United States)

    Feld, Michael; Fröhlich, Bernd; Vogt, Enrico; Koschorreck, Marco; Köhl, Michael

    2011-11-30

    Pairing of fermions is ubiquitous in nature, underlying many phenomena. Examples include superconductivity, superfluidity of (3)He, the anomalous rotation of neutron stars, and the crossover between Bose-Einstein condensation of dimers and the BCS (Bardeen, Cooper and Schrieffer) regime in strongly interacting Fermi gases. When confined to two dimensions, interacting many-body systems show even more subtle effects, many of which are not understood at a fundamental level. Most striking is the (as yet unexplained) phenomenon of high-temperature superconductivity in copper oxides, which is intimately related to the two-dimensional geometry of the crystal structure. In particular, it is not understood how the many-body pairing is established at high temperature, and whether it precedes superconductivity. Here we report the observation of a many-body pairing gap above the superfluid transition temperature in a harmonically trapped, two-dimensional atomic Fermi gas in the regime of strong coupling. Our measurements of the spectral function of the gas are performed using momentum-resolved photoemission spectroscopy, analogous to angle-resolved photoemission spectroscopy in the solid state. Our observations mark a significant step in the emulation of layered two-dimensional strongly correlated superconductors using ultracold atomic gases.

  14. Matched-pair classification

    Energy Technology Data Exchange (ETDEWEB)

    Theiler, James P [Los Alamos National Laboratory

    2009-01-01

    Following an analogous distinction in statistical hypothesis testing, we investigate variants of machine learning where the training set comes in matched pairs. We demonstrate that even conventional classifiers can exhibit improved performance when the input data has a matched-pair structure. Online algorithms, in particular, converge quicker when the data is presented in pairs. In some scenarios (such as the weak signal detection problem), matched pairs can be generated from independent samples, with the effect not only doubling the nominal size of the training set, but of providing the structure that leads to better learning. A family of 'dipole' algorithms is introduced that explicitly takes advantage of matched-pair structure in the input data and leads to further performance gains. Finally, we illustrate the application of matched-pair learning to chemical plume detection in hyperspectral imagery.

  15. Successful same-sex pairing in Laysan albatross.

    Science.gov (United States)

    Young, Lindsay C; Zaun, Brenda J; Vanderwerf, Eric A

    2008-08-23

    Unrelated same-sex individuals pairing together and cooperating to raise offspring over many years is a rare occurrence in the animal kingdom. Cooperative breeding, in which animals help raise offspring that are not their own, is often attributed to kin selection when individuals are related, or altruism when individuals are unrelated. Here we document long-term pairing of unrelated female Laysan albatross (Phoebastria immutabilis) and show how cooperation may have arisen as a result of a skewed sex ratio in this species. Thirty-one per cent of Laysan albatross pairs on Oahu were female-female, and the overall sex ratio was 59% females as a result of female-biased immigration. Female-female pairs fledged fewer offspring than male-female pairs, but this was a better alternative than not breeding. In most female-female pairs that raised a chick in more than 1 year, at least one offspring was genetically related to each female, indicating that both females had opportunities to reproduce. These results demonstrate how changes in the sex ratio of a population can shift the social structure and cause cooperative behaviour to arise in a monogamous species, and they also underscore the importance of genetically sexing monomorphic species.

  16. Identification of evolutionary hotspots based on genetic data from multiple terrestrial and aquatic taxa and gap analysis of hotspots in protected lands encompassed by the South Atlantic Landscape Conservation Cooperative.

    Science.gov (United States)

    Robinson, J.; Snider, M.; Duke, J.; Moyer, G.R.

    2014-01-01

     The southeastern United States is a recognized hotspot of biodiversity for a variety of aquatic taxa, including fish, amphibians, and mollusks. Unfortunately, the great diversity of the area is accompanied by a large proportion of species at risk of extinction . Gap analysis was employed to assess the representation of evolutionary hotspots in protected lands w h ere an evolutionary hotspot was defined as an area with high evolutionary potential and measured by atypical patterns of genetic divergence, genetic diversity, and to a lesser extent genetic similarity across multiple terrestrial or aquatic taxa. A survey of the primary literature produced 16 terrestrial and 14 aquatic genetic datasets for estimation of genetic divergence and diversity. Relative genetic diversity and divergence values for each terrestrial and aquatic dataset were used for interpolation of multispecies genetic surfaces and subsequent visualization using ArcGIS. The multispecies surfaces interpolated from relative divergences and diversity data identified numerous evolutionary hotspots for both terrestrial and aquatic taxa , many of which were afforded some current protection. For instance, 14% of the cells identified as hotspots of aquatic diversity were encompassed by currently protected areas. Additionally, 25% of the highest 1% of terrestrial diversity cells were afforded some level of protection. In contrast, areas of high and low divergence among species, and areas of high variance in diversity were poorly represented in the protected lands. Of particular interest were two areas that were consistently identified by several different measures as important from a conservation perspective. These included an area encompassing the panhandle of Florida and southern Georgia near the Apalachicola National Forest (displaying varying levels of genetic divergence and greater than average levels of genetic diversity) and a large portion of the coastal regions of North and South Carolina

  17. On the pairing effects in triaxial nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Oudih, M. R. [Laboratoire de Physique Théorique, Faculté de Physique,USTHB BP 32, El Alia, 16111 Bab Ezzouar, Algiers (Algeria); Fellah, M.; Allal, N. H. [Centre de Recherche Nucléaire d' Alger, 2 Bd. Frantz Fanon, BP. 399 Alger-Gare, Algiers, Algeria and Laboratoire de Physique Théorique, Faculté de Physique,USTHB BP 32, El Alia, 16111 Bab Ezzouar, Algiers (Algeria)

    2014-03-05

    Triaxial deformation effect on the pairing correlations is studied in the framework of the Skyrme Hartree-Fock-Bogoliubov theory. Quantities such as binding energy, gap parameter and particle-number fluctuation are considered in neutron-rich Mo isotopes. The results are compared with those of axially symmetric calculation and with available experimental data. The role played by the particle-number projection is outlined.

  18. Sub-Cultural Determinants of Cooperative and Competitive Behavior.

    Science.gov (United States)

    Madsen, Millard

    The three studies involved attempt to assess the nature of cooperative and competitive behavior of young children in different socioeconomic classes. In the first study, 36 pairs of Head Start children, representing Mexican-American, Negro and Caucasian ethnic groups, were investigated concerning their cooperative-competitive behavior in relation…

  19. The First Field Experience: Perspectives of Preservice and Cooperating Teachers

    Science.gov (United States)

    O'Brian, Mary; Stoner, Julia; Appel, Kelli; House, Jennifer J.

    2007-01-01

    This study examined perspectives of field experiences among preservice teachers and their cooperating teachers because of debate in the politically charged atmosphere of No Child Left Behind regarding teacher preparation programs. Nine pairs of preservice and cooperating teachers were observed and interviewed over the course of a semester to…

  20. Critical Schwinger Pair Production.

    Science.gov (United States)

    Gies, Holger; Torgrimsson, Greger

    2016-03-04

    We investigate Schwinger pair production in spatially inhomogeneous electric backgrounds. A critical point for the onset of pair production can be approached by fields that marginally provide sufficient electrostatic energy for an off-shell long-range electron-positron fluctuation to become a real pair. Close to this critical point, we observe features of universality which are analogous to continuous phase transitions in critical phenomena with the pair-production rate serving as an order parameter: electric backgrounds can be subdivided into universality classes and the onset of pair production exhibits characteristic scaling laws. An appropriate design of the electric background field can interpolate between power-law scaling, essential Berezinskii-Kosterlitz-Thouless-type scaling, and a power-law scaling with log corrections. The corresponding critical exponents only depend on the large-scale features of the electric background, whereas the microscopic details of the background play the role of irrelevant perturbations not affecting criticality.

  1. Stereo pairs in Astrophysics

    CERN Document Server

    Vogt, Frédéric

    2011-01-01

    Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation of astrophysical data. Here, we review the main theoretical aspects of stereoscopy, and present a tutorial to easily create stereo pairs using Python. We then describe how stereo pairs provide a way to incorporate 3D data in 2D publications of standard journals. We illustrate the use of stereo pairs with one conceptual and two Astrophysical science examples: an integral field spectroscopy study of a supernova remnant, and numerical simulations of a relativistic AGN jet. We also use these examples to make the case that stereo pairs are not merely an ostentatious way to present data, but an enhancement in the communication of scientific results in publications because they prov...

  2. Critical Schwinger pair production

    CERN Document Server

    Gies, Holger

    2015-01-01

    We investigate Schwinger pair production in spatially inhomogeneous electric backgrounds. A critical point for the onset of pair production can be approached by fields that marginally provide sufficient electrostatic energy for an off-shell long-range electron-positron fluctuation to become a real pair. Close to this critical point, we observe features of universality which are analogous to continuous phase transitions in critical phenomena with the pair-production rate serving as an order parameter: electric backgrounds can be subdivided into universality classes and the onset of pair production exhibits characteristic scaling laws. An appropriate design of the electric background field can interpolate between power-law scaling, essential BKT-type scaling and a power-law scaling with log corrections. The corresponding critical exponents only depend on the large-scale features of the electric background, whereas the microscopic details of the background play the role of irrelevant perturbations not affecting ...

  3. Stereo Pair: Patagonia, Argentina

    Science.gov (United States)

    2000-01-01

    This view of northern Patagonia, near El Cain, Argentina shows complexly eroded volcanic terrain, with basalt mesas, sinkholes, landslide debris, playas, and relatively few integrated drainage channels. Surrounding this site (but also extending far to the east) is a broad plateau capped by basalt, the Meseta de Somuncura. Here, near the western edge of the plateau, erosion has broken through the basalt cap in a variety of ways. On the mesas, water-filled sinkholes (lower left) are most likely the result of the collapse of old lava tubes. Along the edges of the mesas (several locations) the basalt seems to be sliding away from the plateau in a series of slices. Water erosion by overland flow is also evident, particularly in canyons where vegetation blankets the drainage channels (green patterns, bottom of image). However, overland water flow does not extend very far at any location. This entire site drains to local playas, some of which are seen here (blue). While the water can reach the playas and then evaporate, what becomes of the eroded rock debris? Wind might excavate some of the finer eroded debris, but the fate of much of the missing bedrock remains mysterious.This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7 satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7

  4. Cooperation under indirect reciprocity and imitative trust.

    Directory of Open Access Journals (Sweden)

    Serguei Saavedra

    Full Text Available Indirect reciprocity, a key concept in behavioral experiments and evolutionary game theory, provides a mechanism that allows reciprocal altruism to emerge in a population of self-regarding individuals even when repeated interactions between pairs of actors are unlikely. Recent empirical evidence show that humans typically follow complex assessment strategies involving both reciprocity and social imitation when making cooperative decisions. However, currently, we have no systematic understanding of how imitation, a mechanism that may also generate negative effects via a process of cumulative advantage, affects cooperation when repeated interactions are unlikely or information about a recipient's reputation is unavailable. Here we extend existing evolutionary models, which use an image score for reputation to track how individuals cooperate by contributing resources, by introducing a new imitative-trust score, which tracks whether actors have been the recipients of cooperation in the past. We show that imitative trust can co-exist with indirect reciprocity mechanisms up to a threshold and then cooperation reverses -revealing the elusive nature of cooperation. Moreover, we find that when information about a recipient's reputation is limited, trusting the action of third parties towards her (i.e. imitating does favor a higher collective cooperation compared to random-trusting and share-alike mechanisms. We believe these results shed new light on the factors favoring social imitation as an adaptive mechanism in populations of cooperating social actors.

  5. Cooperation under indirect reciprocity and imitative trust.

    Science.gov (United States)

    Saavedra, Serguei; Smith, David; Reed-Tsochas, Felix

    2010-10-27

    Indirect reciprocity, a key concept in behavioral experiments and evolutionary game theory, provides a mechanism that allows reciprocal altruism to emerge in a population of self-regarding individuals even when repeated interactions between pairs of actors are unlikely. Recent empirical evidence show that humans typically follow complex assessment strategies involving both reciprocity and social imitation when making cooperative decisions. However, currently, we have no systematic understanding of how imitation, a mechanism that may also generate negative effects via a process of cumulative advantage, affects cooperation when repeated interactions are unlikely or information about a recipient's reputation is unavailable. Here we extend existing evolutionary models, which use an image score for reputation to track how individuals cooperate by contributing resources, by introducing a new imitative-trust score, which tracks whether actors have been the recipients of cooperation in the past. We show that imitative trust can co-exist with indirect reciprocity mechanisms up to a threshold and then cooperation reverses -revealing the elusive nature of cooperation. Moreover, we find that when information about a recipient's reputation is limited, trusting the action of third parties towards her (i.e. imitating) does favor a higher collective cooperation compared to random-trusting and share-alike mechanisms. We believe these results shed new light on the factors favoring social imitation as an adaptive mechanism in populations of cooperating social actors.

  6. Pairing in bulk nuclear matter beyond BCS

    CERN Document Server

    Ding, D; Dickhoff, W H; Dussan, H; Rios, A; Polls, A

    2014-01-01

    The influence of short-range correlations on the spectral distribution of neutrons is incorporated in the solution of the gap equation for the ${}^3P_2-{}^3F_2$ coupled channel in pure neutron matter. This effect is studied for different realistic interactions including one based on chiral perturbation theory. The gap in this channel vanishes at all relevant densities due to the treatment of these correlations. We also consider the effect of long-range correlations by including polarization terms in addition to the bare interaction which allow the neutrons to exchange density and spin fluctuations governed by the strength of Landau parameters allowed to have reasonable values consistent with the available literature. Preliminary results indicate that reasonable values of these parameters do not generate a gap in the ${}^3P_2-{}^3F_2$ coupled channel either for all three realistic interactions although the pairing interaction becomes slightly more attractive.

  7. Pairing in Fermionic Systems Basic Concepts and Modern Applications

    CERN Document Server

    Clark, John W; Alford, Mark

    2006-01-01

    Cooper pairing of fermions is a profound phenomenon that has become very important in many different areas of physics in the recent past. This book brings together, for the first time, experts from various fields involving Cooper pairing, at the level of BCS theory and beyond, including the study of novel states of matter such as ultracold atomic gases, nuclear systems at the extreme, and quark matter with application to neutron stars. Cross-disciplinary in nature, the book will be of interest to physicists in many different specialties, including condensed matter, nuclear, high-energy, and as

  8. PREFACE: Cooperative dynamics Cooperative dynamics

    Science.gov (United States)

    Gov, Nir

    2011-09-01

    The dynamics within living cells are dominated by non-equilibrium processes that consume chemical energy (usually in the form of ATP, adenosine triphosphate) and convert it into mechanical forces and motion. The mechanisms that allow this conversion process are mostly driven by the components of the cytoskeleton: (i) directed (polar) polymerization of filaments (either actin or microtubules) and (ii) molecular motors. The forces and motions produced by these two components of the cytoskeleton give rise to the formation of cellular shapes, and drive the intracellular transport and organization. It is clear that these systems present a multi-scale challenge, from the physics of the molecular processes to the organization of many interacting units. Understanding the physical nature of these systems will have a large impact on many fundamental problems in biology and break new grounds in the field of non-equilibrium physics. This field of research has seen a rapid development over the last ten years. Activities in this area range from theoretical and experimental work on the underlying fundamental (bio)physics at the single-molecule level, to investigations (in vivo and in vitro) of the dynamics and patterns of macroscopic pieces of 'living matter'. In this special issue we have gathered contributions that span the whole spectrum of length- and complexity-scales in this field. Some of the works demonstrate how active forces self-organize within the polymerizing cytoskeleton, on the level of cooperative cargo transport via motors or due to active fluxes at the cell membrane. On a larger scale, it is shown that polar filaments coupled to molecular motors give rise to a huge variety of surprising dynamics and patterns: spontaneously looping rings of gliding microtubules, and emergent phases of self-organized filaments and motors in different geometries. All of these articles share the common feature of being out-of-equilibrium, driven by metabolism. As demonstrated here

  9. Sequence and expression analysis of gaps in human chromosome 20

    DEFF Research Database (Denmark)

    Minocherhomji, Sheroy; Seemann, Stefan; Mang, Yuan;

    2012-01-01

    The finished human genome-assemblies comprise several hundred un-sequenced euchromatic gaps, which may be rich in long polypurine/polypyrimidine stretches. Human chromosome 20 (chr 20) currently has three unfinished gaps remaining on its q-arm. All three gaps are within gene-dense regions and....../or overlap disease-associated loci, including the DLGAP4 locus. In this study, we sequenced ~99% of all three unfinished gaps on human chr 20, determined their complete genomic sizes and assessed epigenetic profiles using a combination of Sanger sequencing, mate pair paired-end high-throughput sequencing...... and chromatin, methylation and expression analyses. We found histone 3 trimethylated at Lysine 27 to be distributed across all three gaps in immortalized B-lymphocytes. In one gap, five novel CpG islands were predominantly hypermethylated in genomic DNA from peripheral blood lymphocytes and human cerebellum...

  10. Cooperation in rats playing the iterated Prisoner's Dilemma game.

    Science.gov (United States)

    Wood, Ruth I; Kim, Jessica Y; Li, Grace R

    2016-04-01

    Humans and animals show cooperative behaviour, but our understanding of cooperation among unrelated laboratory animals is limited. A classic test of cooperation is the iterated Prisoner's Dilemma (IPD) game, where two players receive varying payoffs for cooperation or defection in repeated trials. To determine whether unrelated rats cooperate in the IPD, we tested pairs of rats making operant responses to earn food reward in 25 trials/day. The operant chamber was bisected by a metal screen with a retractable lever and pellet dispenser on each side. When levers extended, rats had 2 s to respond. Mutual cooperation (Reward) delivered three pellets each, mutual defection (Punishment) provided no pellets, and unilateral defection (Temptation) gave five pellets to the defector, while the partner (Sucker) received none. In eight pairs of males (RM-) and females (RF-), cooperation was defined by withholding a response. In seven pairs of RM+ males, cooperation was defined by responding on the lever. In males, food restriction significantly inhibited both cooperation and pellets received. There was no effect of dominance status. Males and females made similar numbers of responses under ad libitum feeding. However, neither food restriction nor dominance status affected responses in females. Rats were subsequently tested for reciprocity in 24 alternating trials/day. A response on the lever within 5 s delivered three pellets to the partner. Females made significantly more responses for their cage-mate than males. Responses within pairs were significantly correlated for males, but not for females. For both sexes, responses declined significantly when paired with an unfamiliar partner who never reciprocated ('bad stooge'). These results demonstrate that rats working for food show cooperation in IPD and direct reciprocity. Their responses depend on food availability and responses of their partner.

  11. Predicting the optical gap of conjugated systems

    Science.gov (United States)

    Botelho, Andre Leitao

    The adapted Su-Schrieffer-Heeger model is developed in this work as a tool for in silico prediction of the optical gap of pi-conjugated systems for photovoltaic applications. Full transferability of the model ensures reliable predictive power - excellent agreement with 180 independent experimental data points covering virtually all existing conjugated system types with an accuracy exceeding the time-dependent density functional theory, one of the most accurate first-principles methods. Insights on the structure-property relation of conjugated systems obtained from the model lead to guiding rules for optical gap design: 1) fusing aromatic rings parallel to the conjugated path does not significantly lower the optical gap, 2) fusing rings perpendicularly lowers the optical gap of the monomer, but has a reduced benefit from polymerization, and 3) copolymers take advantage of the lower optical gap of perpendicular fused rings and benefit from further optical gap reduction through added parallel fused rings as electronic communicators. A copolymer of parallel and perpendicular benzodithiophenes, differing only in sulfur atom locations, is proposed as a candidate to achieve the optimal 1.2 eV donor optical gap for organic photovoltaics. For small-molecule organic photovoltaics, substituting the end pairs of carbon atoms on pentacene with sulfur atoms is predicted to lower the optical gap from 1.8 eV to 1.1 eV. Furthermore, the model offers an improvement of orders of magnitude in the computational efficiency over commonly used first-principles tools.

  12. A BCS-like gap in the superconductor SmFeAsO0.85F0.15.

    Science.gov (United States)

    Chen, T Y; Tesanovic, Z; Liu, R H; Chen, X H; Chien, C L

    2008-06-26

    Since the discovery of superconductivity in the high-transition-temperature (high-T(c)) copper oxides two decades ago, it has been firmly established that the CuO(2) plane is essential for superconductivity and gives rise to a host of other very unusual properties. A new family of superconductors with the general composition of LaFeAsO(1-x)F(x) has recently been discovered and the conspicuous lack of the CuO(2) planes raises the tantalizing question of a different pairing mechanism in these oxypnictides. The superconducting gap (its magnitude, structure, and temperature dependence) is intimately related to pairing. Here we report the observation of a single gap in the superconductor SmFeAsO(0.85)F(0.15) with T(c) = 42 K as measured by Andreev spectroscopy. The gap value of 2Delta = 13.34 +/- 0.3 meV gives 2Delta/k(B)T(c) = 3.68 (where k(B) is the Boltzmann constant), close to the Bardeen-Cooper-Schrieffer (BCS) prediction of 3.53. The gap decreases with temperature and vanishes at T(c) in a manner consistent with the BCS prediction, but dramatically different from that of the pseudogap behaviour in the copper oxide superconductors. Our results clearly indicate a nodeless gap order parameter, which is nearly isotropic in size across different sections of the Fermi surface, and are not compatible with models involving antiferromagnetic fluctuations, strong correlations, the t-J model, and the like, originally designed for the high-T(c) copper oxides.

  13. Experimental evidence for s-wave pairing symmetry in superconducting Cu(x)Bi2Se3 single crystals using a scanning tunneling microscope.

    Science.gov (United States)

    Levy, Niv; Zhang, Tong; Ha, Jeonghoon; Sharifi, Fred; Talin, A Alec; Kuk, Young; Stroscio, Joseph A

    2013-03-15

    Topological superconductors represent a newly predicted phase of matter that is topologically distinct from conventional superconducting condensates of Cooper pairs. As a manifestation of their topological character, topological superconductors support solid-state realizations of Majorana fermions at their boundaries. The recently discovered superconductor Cu(x)Bi(2)Se(3) has been theoretically proposed as an odd-parity superconductor in the time-reversal-invariant topological superconductor class, and point-contact spectroscopy measurements have reported the observation of zero-bias conductance peaks corresponding to Majorana states in this material. Here we report scanning tunneling microscopy measurements of the superconducting energy gap in Cu(x)Bi(2)Se(3) as a function of spatial position and applied magnetic field. The tunneling spectrum shows that the density of states at the Fermi level is fully gapped without any in-gap states. The spectrum is well described by the Bardeen-Cooper-Schrieffer theory with a momentum independent order parameter, which suggests that Cu(x)Bi(2)Se(3) is a classical s-wave superconductor contrary to previous expectations and measurements.

  14. Supply and Marketing Cooperatives

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ China Supply and Marketing Cooperatives Council of CCPIT was established in March 1996. It is an institution under direct leadership of China Supply and Market-ing Cooperatives and at the same time a branch of China Council for Promotion of International Trade, with its major task to promoting and facilitating export-oriented economic trade and technological cooper-ation of the national supply and marketing cooperative system.

  15. Adaptive Pairing Reversible Watermarking.

    Science.gov (United States)

    Dragoi, Ioan-Catalin; Coltuc, Dinu

    2016-05-01

    This letter revisits the pairwise reversible watermarking scheme of Ou et al., 2013. An adaptive pixel pairing that considers only pixels with similar prediction errors is introduced. This adaptive approach provides an increased number of pixel pairs where both pixels are embedded and decreases the number of shifted pixels. The adaptive pairwise reversible watermarking outperforms the state-of-the-art low embedding bit-rate schemes proposed so far.

  16. The photon PDF in events with rapidity gaps

    Energy Technology Data Exchange (ETDEWEB)

    Harland-Lang, L.A. [University College London, Department of Physics and Astronomy, London (United Kingdom); Khoze, V.A. [Durham University, Institute for Particle Physics Phenomenology, Durham (United Kingdom); NRC Kurchatov Institute, Petersburg Nuclear Physics Institute, Moscow (Russian Federation); Ryskin, M.G. [NRC Kurchatov Institute, Petersburg Nuclear Physics Institute, Moscow (Russian Federation)

    2016-05-15

    We consider photon-initiated events with large rapidity gaps in proton-proton collisions, where one or both protons may break up. We formulate a modified photon PDF that accounts for the specific experimental rapidity gap veto, and demonstrate how the soft survival probability for these gaps may be implemented consistently. Finally, we present some phenomenological results for the two-photon induced production of lepton and W boson pairs. (orig.)

  17. Stereo pairs in Astrophysics

    Science.gov (United States)

    Vogt, Frédéric; Wagner, Alexander Y.

    2012-01-01

    Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation of astrophysical data. Here, we review the main theoretical aspects of stereoscopy, and present a tutorial to easily create stereo pairs using Python. We then describe how stereo pairs provide a way to incorporate 3D data in 2D publications of standard journals. We illustrate the use of stereo pairs with one conceptual and two Astrophysical science examples: an integral field spectroscopy study of a supernova remnant, and numerical simulations of a relativistic AGN jet. We also use these examples to make the case that stereo pairs are not merely an ostentatious way to present data, but an enhancement in the communication of scientific results in publications because they provide the reader with a realistic view of multi-dimensional data, be it of observational or theoretical nature. In recognition of the ongoing 3D expansion in the commercial sector, we advocate an increased use of stereo pairs in Astrophysics publications and presentations as a first step towards new interactive and multi-dimensional publication methods.

  18. Costly advertising and the evolution of cooperation.

    Directory of Open Access Journals (Sweden)

    Markus Brede

    Full Text Available In this paper, I investigate the co-evolution of fast and slow strategy spread and game strategies in populations of spatially distributed agents engaged in a one off evolutionary dilemma game. Agents are characterized by a pair of traits, a game strategy (cooperate or defect and a binary 'advertising' strategy (advertise or don't advertise. Advertising, which comes at a cost [Formula: see text], allows investment into faster propagation of the agents' traits to adjacent individuals. Importantly, game strategy and advertising strategy are subject to the same evolutionary mechanism. Via analytical reasoning and numerical simulations I demonstrate that a range of advertising costs exists, such that the prevalence of cooperation is significantly enhanced through co-evolution. Linking costly replication to the success of cooperators exposes a novel co-evolutionary mechanism that might contribute towards a better understanding of the origins of cooperation-supporting heterogeneity in agent populations.

  19. Costly Advertising and the Evolution of Cooperation

    Science.gov (United States)

    Brede, Markus

    2013-01-01

    In this paper, I investigate the co-evolution of fast and slow strategy spread and game strategies in populations of spatially distributed agents engaged in a one off evolutionary dilemma game. Agents are characterized by a pair of traits, a game strategy (cooperate or defect) and a binary ‘advertising’ strategy (advertise or don’t advertise). Advertising, which comes at a cost , allows investment into faster propagation of the agents’ traits to adjacent individuals. Importantly, game strategy and advertising strategy are subject to the same evolutionary mechanism. Via analytical reasoning and numerical simulations I demonstrate that a range of advertising costs exists, such that the prevalence of cooperation is significantly enhanced through co-evolution. Linking costly replication to the success of cooperators exposes a novel co-evolutionary mechanism that might contribute towards a better understanding of the origins of cooperation-supporting heterogeneity in agent populations. PMID:23861752

  20. Costly advertising and the evolution of cooperation.

    Science.gov (United States)

    Brede, Markus

    2013-01-01

    In this paper, I investigate the co-evolution of fast and slow strategy spread and game strategies in populations of spatially distributed agents engaged in a one off evolutionary dilemma game. Agents are characterized by a pair of traits, a game strategy (cooperate or defect) and a binary 'advertising' strategy (advertise or don't advertise). Advertising, which comes at a cost [Formula: see text], allows investment into faster propagation of the agents' traits to adjacent individuals. Importantly, game strategy and advertising strategy are subject to the same evolutionary mechanism. Via analytical reasoning and numerical simulations I demonstrate that a range of advertising costs exists, such that the prevalence of cooperation is significantly enhanced through co-evolution. Linking costly replication to the success of cooperators exposes a novel co-evolutionary mechanism that might contribute towards a better understanding of the origins of cooperation-supporting heterogeneity in agent populations.

  1. A photonic thermalization gap in disordered lattices

    CERN Document Server

    Kondakci, H E; Saleh, B E A

    2016-01-01

    The formation of gaps -- forbidden ranges in the values of a physical parameter -- is a ubiquitous feature of a variety of physical systems: from energy bandgaps of electrons in periodic lattices and their analogs in photonic, phononic, and plasmonic systems to pseudo energy gaps in aperiodic quasicrystals. Here, we report on a `thermalization' gap for light propagating in finite disordered structures characterized by disorder-immune chiral symmetry -- the appearance of the eigenvalues and eigenvectors in skew-symmetric pairs. In this class of systems, the span of sub- thermal photon statistics is inaccessible to input coherent light, which -- once the steady state is reached -- always emerges with super-thermal statistics no matter how small the disorder level. We formulate an independent constraint that must be satisfied by the input field for the chiral symmetry to be `activated' and the gap to be observed. This unique feature enables a new form of photon-statistics interferometry: the deterministic tuning...

  2. Gredos San Diego Cooperative. Cooperate to undertake

    Directory of Open Access Journals (Sweden)

    Carlos de la Higuera

    2012-12-01

    Full Text Available This paper analyzes the cooperative experience through Gredos San Diego model, its institutional approaches and its history from the point of view of management, focusing on the variables that enable the success of a collective ownership institution. First, the author makes a brief analysis of the principles that guide the cooperative, its origins and its current situation, including the development of GSD Cooperative Group. It continues exploring the evolution of management, dividing it into four distinct stages, and concludes with a summary with the findings of the previous president of the cooperative.Received: 23.07.2012Accepted: 10.09.2012

  3. The population genetics of cooperative gene regulation

    Directory of Open Access Journals (Sweden)

    Stewart Alexander J

    2012-09-01

    Full Text Available Abstract Background Changes in gene regulatory networks drive the evolution of phenotypic diversity both within and between species. Rewiring of transcriptional networks is achieved either by changes to transcription factor binding sites or by changes to the physical interactions among transcription factor proteins. It has been suggested that the evolution of cooperative binding among factors can facilitate the adaptive rewiring of a regulatory network. Results We use a population-genetic model to explore when cooperative binding of transcription factors is favored by evolution, and what effects cooperativity then has on the adaptive re-writing of regulatory networks. We consider a pair of transcription factors that regulate multiple targets and overlap in the sets of target genes they regulate. We show that, under stabilising selection, cooperative binding between the transcription factors is favoured provided the amount of overlap between their target genes exceeds a threshold. The value of this threshold depends on several population-genetic factors: strength of selection on binding sites, cost of pleiotropy associated with protein-protein interactions, rates of mutation and population size. Once it is established, we find that cooperative binding of transcription factors significantly accelerates the adaptive rewiring of transcriptional networks under positive selection. We compare our qualitative predictions to systematic data on Saccharomyces cerevisiae transcription factors, their binding sites, and their protein-protein interactions. Conclusions Our study reveals a rich set of evolutionary dynamics driven by a tradeoff between the beneficial effects of cooperative binding at targets shared by a pair of factors, and the detrimental effects of cooperative binding for non-shared targets. We find that cooperative regulation will evolve when transcription factors share a sufficient proportion of their target genes. These findings help to

  4. Cooperative Online Education

    Directory of Open Access Journals (Sweden)

    Morten Flate Paulsen

    2008-07-01

    Full Text Available Cooperative learning seeks to develop virtual learning environments that allow students to have optimal individual freedom within online learning communities. The pedagogical and administrative challenges with regard to accommodating both individual freedom and cooperation are explained in the Theory of Cooperative Freedom. This article shows that cooperative learning can be implemented successfully through a set of instruments or means. To illustrate this with current examples, the article presents NKI Distance Education’s surveys and experiences with cooperative learning. The article also discusses how issues such as web 2.0, transparency, learning partners and individual progression plans relate to cooperative online education.

  5. Pairing and specific heat in hot nuclei

    CERN Document Server

    Gambacurta, Danilo; Sandulescu, Nicu

    2013-01-01

    The thermodynamics of pairing phase-transition in nuclei is studied in the canonical ensemble and treating the pairing correlations in a finite-temperature variation after projection BCS approach (FT-VAP). Due to the restoration of particle number conservation, the pairing gap and the specific heat calculated in the FT-VAP approach vary smoothly with the temperature, indicating a gradual transition from the superfluid to the normal phase, as expected in finite systems. We have checked that the predictions of the FT-VAP approach are very accurate when compared to the results obtained by an exact diagonalization of the pairing Hamiltonian. The influence of pairing correlations on specific heat is analysed for the isotopes $^{161,162}$Dy and $^{171,172}$Yb. It is shown that the FT-VAP approach, applied with a level density provided by mean field calculations and supplemented, at high energies, by the level density of the back-shifted Fermi gas model, can approximate reasonably well the main properties of specifi...

  6. Towards smaller gap microbulks

    CERN Document Server

    Attié, D.; Dafni, T; Ferrer-Ribas, E.; Ferrer-Ribas, E; Ferry, S; Giomataris, Y; Herrera, D C; Iguaz, F J; Irastorza, I G; Kebbiri, M; Papaevangelou, T; de Oliveira, R; Seguí, L; Tomás, A

    2014-01-01

    Small gap Micromegas detectors ( < 50 μm) are expected to be optimal for high pressure applications. Combining the microbulk manufacturing technique with a small gap can result in attractive detectors for rare event detection, in particular double beta decay or dark matter searches. We present novel results obtained with small gap microbulks (25 and 12.5 μm) that have been manufactured recently. For the first time for this type of detectors, we show experimentally that for each amplification gap there is an optimal pressure and that smaller gaps are more suitable for higher pressures.

  7. Antiferromagnetic exchange and spin-fluctuation pairing in cuprate superconductors

    Science.gov (United States)

    Plakida, Nikolay M.

    2006-01-01

    A microscopic theory of superconductivity is formulated within an effective p-d Hubbard model for a CuO2 plane. By applying the Mori-type projection technique, the Dyson equation is derived for the Green functions in terms of Hubbard operators. The antiferromagnetic exchange caused by interband hopping results in pairing of all carries in the conduction subband and high Tc proportional to the Fermi energy. Kinematic interaction in intraband hopping is responsible for the conventional spin-fluctuation pairing. Numerical solution of the gap equation proves the d-wave gap symmetry and defines Tc doping dependence. Oxygen isotope shift and pressure dependence of Tc are also discussed.

  8. Navigating the complex path between the oxytocin receptor gene (OXTR) and cooperation: an endophenotype approach

    OpenAIRE

    Haas, Brian W.; Anderson, Ian W.; Smith, Jessica M.

    2013-01-01

    Although cooperation represents a core facet of human social behavior there exists considerable variability across people in terms of the tendency to cooperate. One factor that may contribute to individual differences in cooperation is a key gene within the oxytocin (OT) system, the OT reception gene (OXTR). In this article, we aim to bridge the gap between the OXTR gene and cooperation by using an endophenotype approach. We present evidence that the association between the OXTR gene and coop...

  9. Evaluating the Cooperative Component in Cooperative Learning: A Quasi-Experimental Study

    Science.gov (United States)

    Emerson, Tisha L. N.; English, Linda K.; McGoldrick, KimMarie

    2015-01-01

    In this study, the authors employed a quasi-experimental research design to examine the efficacy of a cooperative learning pedagogy (i.e., think-pair-share exercises) integrated into sections of microeconomic principles. Materials, exercises, and assessment instruments for all study sections are identical except for the nature of the…

  10. Cooperative Tagging Center (CTC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Cooperative Tagging Center (CTC) began as the Cooperative Game Fish Tagging Program (GTP) at Woods Hole Oceanographic Institute (WHOI) in 1954. The GTP was...

  11. Electric Field Enhancement of Nano Gap of Silver Prisms

    Institute of Scientific and Technical Information of China (English)

    KENZO Yamaguchi; TOMOHIRO Inoue; MASAMITSU Fujii; MASANOBU Haraguchi; TOSHIHIRO Okamoto; MASUO Fukui; SHU Seki; SEIICHI Tagawa

    2007-01-01

    Using numerical calculation, we examine the effects of gap distance of a pair of nano gap silver prisms with rounded corners on the local light intensity enhancement. Two peaks due to localized surface plasmon (LSP) excitation are observed in a wavelength range from 900nm to 300nm. The results demonstrate that peaks at a longer and a shorter wavelength corresponded to dipole-like and quadrupole-like LSP resonances, respectively. It is found that a gap distance up to 20nm provides larger light intensity enhancement than that of a single silver nano prism with rounded corners. Furthermore, nano gap silver prisms are fabricated by direct focused ion beam processing, and we measure the scattering light spectrum of a pair of nano prisms by a confocal optical system.However, the two LSP peaks are not observed in visible range because the sizes of the nano gap and prisms are too large.

  12. Paired fuzzy sets

    DEFF Research Database (Denmark)

    Rodríguez, J. Tinguaro; Franco de los Ríos, Camilo; Gómez, Daniel

    2015-01-01

    In this paper we want to stress the relevance of paired fuzzy sets, as already proposed in previous works of the authors, as a family of fuzzy sets that offers a unifying view for different models based upon the opposition of two fuzzy sets, simply allowing the existence of different types...

  13. Minimal Pairs: Minimal Importance?

    Science.gov (United States)

    Brown, Adam

    1995-01-01

    This article argues that minimal pairs do not merit as much attention as they receive in pronunciation instruction. There are other aspects of pronunciation that are of greater importance, and there are other ways of teaching vowel and consonant pronunciation. (13 references) (VWL)

  14. Au pair trajectories

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    Since 2000, thousands of young Filipino migrants have come to Denmark as au pairs. Officially, they are there to “broaden their cultural horizons” by living temporarily with a Danish host family, but they also conduct domestic labor in exchange for food and money, which allows them to send import...... the Danish au pair scheme therefore speaks to current research on domestic work migration, the transnational family relations of young Filipina migrants and the forms of self-transformation that Filipino migration might engender.......Since 2000, thousands of young Filipino migrants have come to Denmark as au pairs. Officially, they are there to “broaden their cultural horizons” by living temporarily with a Danish host family, but they also conduct domestic labor in exchange for food and money, which allows them to send...... ethnographic component of the dissertation consists of four articles, all emphasizing the au pairs’ agency by viewing their migration as a dynamic personal and social experience. Arguing that Filipina au pairs tend to be understood primarily from the perspective of their precarious situation as domestic...

  15. Anchored paired comparisons

    Science.gov (United States)

    Dalal, E. N.; Handley, J. C.; Wu, W.; Wang, J.

    2008-01-01

    The method of paired comparisons is often used in image quality evaluations. Psychometric scale values for quality judgments are modeled using Thurstone's Law of Comparative Judgment in which distance in a psychometric scale space is a function of the probability of preference. The transformation from psychometric space to probability is a cumulative probability distribution. The major drawback of a complete paired comparison experiment is that every treatment is compared to every other, thus the number of comparisons grows quadratically. We ameliorate this difficulty by performing paired comparisons in two stages, by precisely estimating anchors in the psychometric scale space which are spaced apart to cover the range of scale values and comparing treatments against those anchors. In this model, we employ a generalized linear model where the regression equation has a constant offset vector determined by the anchors. The result of this formulation is a straightforward statistical model easily analyzed using any modern statistics package. This enables model fitting and diagnostics. This method was applied to overall preference evaluations of color pictorial hardcopy images. The results were found to be compatible with complete paired comparison experiments, but with significantly less effort.

  16. Aspectual Pairing in Polish

    NARCIS (Netherlands)

    Młynarczyk, A.K.

    2004-01-01

    The received view on Slavic aspect is that it is intrinsically complex, and that there is little hope of discerning any substantial regularity. We argue that this view is mistaken. We argue that the vast majority of Polish verbs really do come in aspectual pairs and that far from being a mysterious

  17. Extensive Dialogues and Cooperation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ Chinese Taipei On March 23,Chairman Wan Jifei of the China Council for the Promotion of International Trade (CCPIT) and Board Chairman Wang Zhigang of the Taipei World Trade Center (TWTC) signed a cooperation agreement at the Taipei World Trade Tower,marking the new page of the development of cooperation and relations between the two organizations and the establishment of their cooperation mechanism.

  18. Sorting and sustaining cooperation

    DEFF Research Database (Denmark)

    Vikander, Nick

    2013-01-01

    This paper looks at cooperation in teams where some people are selfish and others are conditional cooperators, and where lay-offs will occur at a fixed future date. I show that the best way to sustain cooperation prior to the lay-offs is often in a sorting equilibrium, where conditional cooperato...

  19. Multi-pair states in electron-positron pair creation

    Science.gov (United States)

    Wöllert, Anton; Bauke, Heiko; Keitel, Christoph H.

    2016-09-01

    Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron-positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron-positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron-positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron-positron pairs.

  20. Designing for cooperation - cooperating in design

    DEFF Research Database (Denmark)

    Kyng, Morten

    1991-01-01

    This article will discuss how to design computer applications that enhance the quality of work and products, and will relate the discussion to current themes in the field of Computer-Supported Cooperative Work (CSCW). Cooperation is a key element of computer use and work practice, yet here...... a specific "CSCW approach is not taken." Instead the focus is cooperation as an important aspect of work that should be integrated into most computer support efforts in order to develop successful computer support, however, other aspects such as power, conflict and control must also be considered....

  1. A direct method for computing extreme value (Gumbel) parameters for gapped biological sequence alignments.

    Science.gov (United States)

    Quinn, Terrance; Sinkala, Zachariah

    2014-01-01

    We develop a general method for computing extreme value distribution (Gumbel, 1958) parameters for gapped alignments. Our approach uses mixture distribution theory to obtain associated BLOSUM matrices for gapped alignments, which in turn are used for determining significance of gapped alignment scores for pairs of biological sequences. We compare our results with parameters already obtained in the literature.

  2. Cooperative strategies European perspectives

    CERN Document Server

    Killing, J Peter

    1997-01-01

    Cooperative Strategies: European Perspectives is one of three geographically targeted volumes in which the contributors present the most current research on topics such as advances in theories of cooperative strategies, the formation of cooperative alliances, the dynamics of partner relationships, and the role of information and knowledge in cooperative alliances. Blending conceptual insights with empirical analyses, the contributors highlight commonalities and differences across national, cultural, and trade zones. The chapters in this volume are anchored in a wide set of theoretical approaches, conceptual frameworks, and models, illustrating how rich the area of cooperative strategies is for scholarly inquiry.

  3. Duality between quark-quark and quark-antiquark pairing in 1+1 dimensional large N models

    CERN Document Server

    Thies, M

    2003-01-01

    We identify a canonical transformation which maps the chiral Gross-Neveu model onto a recently proposed Cooper pair model. Baryon number and axial charge are interchanged. The same physics can be described either as chiral symmetry breaking (quark-antiquark pairing) or as superconductivity (quark-quark pairing).

  4. Dilemmas of partial cooperation.

    Science.gov (United States)

    Stark, Hans-Ulrich

    2010-08-01

    Related to the often applied cooperation models of social dilemmas, we deal with scenarios in which defection dominates cooperation, but an intermediate fraction of cooperators, that is, "partial cooperation," would maximize the overall performance of a group of individuals. Of course, such a solution comes at the expense of cooperators that do not profit from the overall maximum. However, because there are mechanisms accounting for mutual benefits after repeated interactions or through evolutionary mechanisms, such situations can constitute "dilemmas" of partial cooperation. Among the 12 ordinally distinct, symmetrical 2 x 2 games, three (barely considered) variants are correspondents of such dilemmas. Whereas some previous studies investigated particular instances of such games, we here provide the unifying framework and concisely relate it to the broad literature on cooperation in social dilemmas. Complementing our argumentation, we study the evolution of partial cooperation by deriving the respective conditions under which coexistence of cooperators and defectors, that is, partial cooperation, can be a stable outcome of evolutionary dynamics in these scenarios. Finally, we discuss the relevance of such models for research on the large biodiversity and variation in cooperative efforts both in biological and social systems.

  5. Bridging the Gap

    OpenAIRE

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska; Murdock, Karen; Schmidt, Iben Julie

    2015-01-01

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures. Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ve...

  6. Bridging the Gap

    DEFF Research Database (Denmark)

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska;

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures.......Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures....

  7. Gap and density theorems

    CERN Document Server

    Levinson, N

    1940-01-01

    A typical gap theorem of the type discussed in the book deals with a set of exponential functions { \\{e^{{{i\\lambda}_n} x}\\} } on an interval of the real line and explores the conditions under which this set generates the entire L_2 space on this interval. A typical gap theorem deals with functions f on the real line such that many Fourier coefficients of f vanish. The main goal of this book is to investigate relations between density and gap theorems and to study various cases where these theorems hold. The author also shows that density- and gap-type theorems are related to various propertie

  8. Protected Flux Pairing Qubit

    Science.gov (United States)

    Bell, Matthew; Zhang, Wenyuan; Ioffe, Lev; Gershenson, Michael

    2014-03-01

    We have studied the coherent flux tunneling in a qubit containing two submicron Josephson junctions shunted by a superinductor (a dissipationless inductor with an impedance much greater than the resistance quantum). The two low energy quantum states of this device, " open="|"> 0 and " open="|"> 1, are represented by even and odd number of fluxes in the loop, respectively. This device is dual to the charge pairing Josephson rhombi qubit. The spectrum of the device, studied by microwave spectroscopy, reflects the interference between coherent quantum phase slips in the two junctions (the Aharonov-Casher effect). The time domain measurements demonstrate the suppression of the qubit's energy relaxation in the protected regime, which illustrates the potential of this flux pairing device as a protected quantum circuit. Templeton Foundation, NSF, and ARO.

  9. To cooperate or not to cooperate

    DEFF Research Database (Denmark)

    Wessels, Josepha Ivanka

    To Cooperate or not to Cooperate...? discusses results of a research project to study the rehabilitation of 1500-year old water tunnels, so called "qanats", in Syria. Communities all over the world are using traditional technologies to extract drinkingwater, irrigate their lands and feed their li......To Cooperate or not to Cooperate...? discusses results of a research project to study the rehabilitation of 1500-year old water tunnels, so called "qanats", in Syria. Communities all over the world are using traditional technologies to extract drinkingwater, irrigate their lands and feed...... their livestock. But these often sustainable and ancient ways to make use of groundwater are in rapid decline worldwide. A research project started in 1999 to study the rehabilitation of 1500-year old water tunnels called "qanats"in Syria. To Cooperate or not to Cooperate...? discusses results and outcomes...... of this research project. The main objective of this research is to better understand the proces of collective maintenance of these ancient water tunnels. The study evaluates the social, cultural, political and environmental factors that have driven abandonment and decay of qanats in Syria. It tries to reconcile...

  10. SRTM Stereo Pair: Wheeler Ridge, California

    Science.gov (United States)

    2000-01-01

    Wheeler Ridge and vicinity, California, is a site of major tectonic activity, both historically and over recent geologic time. The epicenter of the 7.5 magnitude Kern County earthquake occurred here on July 21,1952, and numerous geologic and topographic features indicate rapid geologic processes. The ridge itself (upper-right center) is a geologic fold that is growing out of the southern San Joaquin Valley. A prominent 'wind gap,' now used for passage of the California aquaduct (with the aid of a pumping station), is evidence that the ridge grew faster than tranversing streams could erode down. Nearby abrupt and/or landslid mountain fronts similarly indicate a vigorous tectonic setting here, just north of the San Andreas fault. The Interstate 5 freeway can be seen crossing agricultural fields on the right and entering the very rugged and steep Grapevine Canyon toward the bottom.This stereoscopic image was generated by draping a Landsat satellite image over a preliminary Shuttle Radar Topography Mission (SRTM) elevation model. Two differing perspectives were then calculated, one for each eye. They can be seen in 3-D by viewing the left image with the right eye and the right image with the left eye (cross-eyed viewing), or by downloading and printing the image pair and viewing them with a stereoscope. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter resolution of most Landsat images and will substantially help in analyses of the large and growing Landsat image archive.The elevation data used in this image was acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994

  11. Stationary Vortices and Pair Currents in a Trapped Fermion Superfluid

    Science.gov (United States)

    Capuzzi, P.; Hernández, E. S.; Szybisz, L.

    2015-05-01

    We examine the effects of stationary vortices in superfluid Li atoms at zero temperature in the frame of the recently developed fluiddynamical scheme, that includes the pair density and its associated pair current and pair kinetic energy in addition to the fields appearing in the hydrodynamical description of normal fluids. In this frame, the presence of any particle velocity field gives rise to the appearance of a pair current. As an illustration, we consider a stationary vortex with cylindrical geometry in an unpolarized fluid, and examine the effects of the rotational velocity field on the spatial structure of the equilibrium gap and the profiles of the pair current. We show that the latter is intrinsically complex and its imaginary part is the source of a radial drift for the velocity field. We discuss the consequences on the stationary regime.

  12. A new threshold proxy signature scheme from bilinear pairings

    Institute of Scientific and Technical Information of China (English)

    QIAN Haifeng; CAO Zhenfu; XUE Qingshui

    2004-01-01

    Based on the GDH signature (short signature scheme) a probabilistic signature scheme is proposed in this paper with security proof. Then a new threshold proxy signature from bilinear pairings is proposed as well by using the new probabilistic signature scheme and the properties of the Gap Diffie-Hellman (GDH) group (where the Computational Diffie-Hellman problem is hard but the Decisional Diffie-Hellman problem is easy to solve). Our constructions are based on the recently proposed GDH signature scheme of Bonel et al.'s article. Bilinear pairings could be built from Weil pairing or Tate pairing. So most our constructions would be simpler, but still with high security. The proposed threshold proxy signature is the first one which is built from bilinear pairings. At the end of this paper security and performance of the threshold proxy signature scheme is also analyzed.

  13. Preparing projected entangled pair states on a quantum computer.

    Science.gov (United States)

    Schwarz, Martin; Temme, Kristan; Verstraete, Frank

    2012-03-16

    We present a quantum algorithm to prepare injective projected entangled pair states (PEPS) on a quantum computer, a class of open tensor networks representing quantum states. The run time of our algorithm scales polynomially with the inverse of the minimum condition number of the PEPS projectors and, essentially, with the inverse of the spectral gap of the PEPS's parent Hamiltonian.

  14. Expectation and cooperation in prisoner's dilemmas: The moderating role of game riskiness.

    Science.gov (United States)

    Ng, Gary Ting Tat; Au, Wing Tung

    2016-04-01

    This paper investigated the effect of risk orientation, game riskiness, and expectation of cooperation on cooperation in one-shot prisoner's dilemmas (PD). Participants in pairs played PD games that varied on game riskiness such that for half of the games cooperation was more risky than defection (more risky games) while for another half cooperation was less risky (less risky games). They estimated how likely it was that the other player was going to cooperate (expectation of cooperation) before they made their cooperation/defection decision on each game. Supporting the Goal/Expectation Hypothesis, we replicated the effect that expectation of cooperation enhanced cooperation. We also found that risk-seeking individuals cooperated more in more risky games whereas risk-averse individuals cooperated more in less risky games. More importantly, we found that game riskiness moderated the effect of expectation of cooperation on cooperation. The positive effect of expectation of cooperation on cooperation was stronger for more risky games than for less risky games. Our results illustrated how the relation between expectation and cooperation as stipulated by the Goal/Expectation Hypothesis was moderated by riskiness of the situations.

  15. Ground-state and Pairing Properties of Pr Isotopes in RMF Theory

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The ground-state and pairing properties of Pr (Z=59) isotopes have been investigated in therelativistic mean-field (RMF). The pairing correlation is studied in Bardeen-Cooper-Schrieffer (BCS) approximation and the pairingforces are taken to be isospin dependent. The ’blocking’ method is adopted to deal with unpaired odd

  16. Bridging a Cultural Gap

    Science.gov (United States)

    Leviatan, Talma

    2008-01-01

    There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmes--aimed at bridging the gap between high-school mathematics and tertiary mathematics--is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of a…

  17. Senseless Extravagance, Shocking Gaps

    Science.gov (United States)

    Weissbourd, Richard; Dodge, Trevor

    2012-01-01

    Although most people in the United States believe, at least theoretically, in educational equality, fewer and fewer appear to care about the resource gaps between affluent and poor schools, says Weissbourd. He illustrates these gaps with vivid descriptions of what he calls an "opulence arms race" among affluent independent schools, but…

  18. Bridge the Gap

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2017-01-01

    This article focuses on photo projects organised for teenage refugees by the Society for Humanistic Photography (Berlin, Germany). These projects, named Bridge the Gap I (2015), and Bridge the Gap II (2016), were carried out in Berlin and brought together teenagers with refugee and German...

  19. Addressing the military gap in the western Balkans and closing the gap through regional cooperation

    Science.gov (United States)

    2017-06-09

    kindness, and hospitality . Thank you to Mrs. Venita Krueger and Mrs. Ann Chapman for their assistance with the formatting and editing of this...my entire life. I will never forget the hospitality of the American families, sponsors, and friends, Mark and Vera Samson, Sam and Vicky Casmus, and...source of Albanian’s economy is from agriculture, minerals, oil, natural gas, and tourism . The Albanian unemployment rate is quite high (estimated at

  20. Optimized measurement of gaps

    Science.gov (United States)

    Harding, Kevin; Ramamurthy, Rajesh

    2017-05-01

    Gaps are important in a wide range of measurements in manufacturing, from the fitting of critical assemblies too cosmetic features on cars. There are a variety of potential sensors that can measure a gap opening, each with aspects of gap measurements that they do well and other aspects where the technology may lack capability. This paper provides a review of a wide range of optical gages from structured light to passive systems and from line to area measurement. Each technology is considered relative to the ability to accurately measure a gap, including issues of edge effects, edge shape, surface finish, and transparency. Finally, an approach will be presented for creating an optimize measurement off gap openings for critical assembly applications.

  1. Au pairs on Facebook

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Ethnographers are increasingly making use of Facebook to acquire access and general acquaintance with their field of study. However, little has been written on how Facebook is used methodologically in research that does not have social media sites as the main focus of interest. This article argues...... that engagement with Facebook as a methodological tool can be useful in research among migrants in highly politicised fields. Pointing to a discursive construction of Filipina au pairs as victims of labour exploitation, the article shows how fieldwork on Facebook enables the exploration of the ways in which...... and on Facebook....

  2. Multispecies pair annihilation reactions.

    Science.gov (United States)

    Deloubrière, Olivier; Hilhorst, Henk J; Täuber, Uwe C

    2002-12-16

    We consider diffusion-limited reactions A(i)+A(j)--> (12 and d> or =2, we argue that the asymptotic density decay for such mutual annihilation processes with equal rates and initial densities is the same as for single-species pair annihilation A+A-->. In d=1, however, particle segregation occurs for all q< infinity. The total density decays according to a q dependent power law, rho(t) approximately t(-alpha(q)). Within a simplified version of the model alpha(q)=(q-1)/2q can be determined exactly. Our findings are supported through Monte Carlo simulations.

  3. Au pairs on Facebook

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Ethnographers are increasingly making use of Facebook to acquire access and general acquaintance with their field of study. However, little has been written on how Facebook is used methodologically in research that does not have social media sites as the main focus of interest. This article argues...... that engagement with Facebook as a methodological tool can be useful in research among migrants in highly politicised fields. Pointing to a discursive construction of Filipina au pairs as victims of labour exploitation, the article shows how fieldwork on Facebook enables the exploration of the ways in which...... and on Facebook....

  4. Cooperative wireless communications

    CERN Document Server

    Zhang, Yan

    2009-01-01

    Cooperative devices and mechanisms are increasingly important to enhance the performance of wireless communications and networks, with their ability to decrease power consumption and packet loss rate and increase system capacity, computation, and network resilience. Considering the wide range of applications, strategies, and benefits associated with cooperative wireless communications, researchers and product developers need a succinct understanding of relevant theory, fundamentals, and techniques to navigate this challenging field. ""Cooperative Wireless Communications"" provides just that. I

  5. Better stay together: pair bond duration increases individual fitness independent of age-related variation

    OpenAIRE

    Sánchez-Macouzet, Oscar; Rodríguez, Cristina; Drummond, Hugh

    2014-01-01

    Prolonged pair bonds have the potential to improve reproductive performance of socially monogamous animals by increasing pair familiarity and enhancing coordination and cooperation between pair members. However, this has proved very difficult to test robustly because of important confounds such as age and reproductive experience. Here, we address limitations of previous studies and provide a rigorous test of the mate familiarity effect in the socially monogamous blue-footed booby, Sula neboux...

  6. Cooperative Station History Forms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Various forms, photographs and correspondence documenting the history of Cooperative station instrumentation, location changes, inspections, and...

  7. Futures for energy cooperatives

    Energy Technology Data Exchange (ETDEWEB)

    None

    1981-01-01

    A listing of Federal agencies and programs with potential funding for community-scale cooperatives using conservation measures and solar technologies is presented in Section 1. Section 2 presents profiles of existing community energy cooperatives describing their location, history, membership, services, sources of finance and technical assistance. A condensed summary from a recent conference on Energy Cooperatives featuring notes on co-op members' experiences, problems, and opportunities is presented in Section 3. Section 4 lists contacts for additional information. A National Consumer Cooperative Bank Load Application is shown in the appendix.

  8. Cooperation or Silent Rivalry?

    DEFF Research Database (Denmark)

    Zank, Wolfgang

    2010-01-01

    a gravitational pull which goes beyond economic problems. Furthermore, the EU has gradually built up a coherent policy on many fields. The EU has become the “reform anchor” and most important cooperation partner for Egypt. The progress towards increasing Egypt’s “Stake in the Internal Market” places cooperation...... on an increasingly institutionalized basis. In terms of military cooperation the US is still the partner for Egypt. But outside the military sphere institutionalized cooperation is comparatively week. In particular the failure of the US to conclude a free-trade agreement has been crucial. But it would be wrong...

  9. Parasites may help stabilize cooperative relationships

    Directory of Open Access Journals (Sweden)

    Little Ainslie EF

    2009-06-01

    Full Text Available Abstract Background The persistence of cooperative relationships is an evolutionary paradox; selection should favor those individuals that exploit their partners (cheating, resulting in the breakdown of cooperation over evolutionary time. Our current understanding of the evolutionary stability of mutualisms (cooperation between species is strongly shaped by the view that they are often maintained by partners having mechanisms to avoid or retaliate against exploitation by cheaters. In contrast, we empirically and theoretically examine how additional symbionts, specifically specialized parasites, potentially influence the stability of bipartite mutualistic associations. In our empirical work we focus on the obligate mutualism between fungus-growing ants and the fungi they cultivate for food. This mutualism is exploited by specialized microfungal parasites (genus Escovopsis that infect the ant's fungal gardens. Using sub-colonies of fungus-growing ants, we investigate the interactions between the fungus garden parasite and cooperative and experimentally-enforced uncooperative ("cheating" pairs of ants and fungi. To further examine if parasites have the potential to help stabilize some mutualisms we conduct Iterative Prisoner's Dilemma (IPD simulations, a common framework for predicting the outcomes of cooperative/non-cooperative interactions, which incorporate parasitism as an additional factor. Results In our empirical work employing sub-colonies of fungus-growing ants, we found that Escovopsis-infected sub-colonies composed of cheating populations of ants or fungi lost significantly more garden biomass than sub-colonies subjected to infection or cheating (ants or fungi alone. Since the loss of fungus garden compromises the fitness of both mutualists, our findings suggest that the potential benefit received by the ants or fungi for cheating is outweighed by the increased concomitant cost of parasitism engendered by non-cooperation (cheating. IPD

  10. Searching for Pair Halos

    Science.gov (United States)

    Fallon, Lisa; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Behera, B.; Bernlühr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Conrad, J.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Domainko, A. Djannati-Ataü W.; Drury, L. O'c.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fürster, A.; Fontaine, G.; Füssling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Güring, D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzynski, K.; Katz, U.; Kaufmann, S.; Kerschhaggl, M.; Khangulyan, D.; Khálifi, B.; Keogh, D.; Klochkov, D.; Kluzniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Lamanna, G.; Lenain, J.-P.; Lohse, T.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Mau-Rin, D.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Ona Wilhelmi, E.; Opitz, B.; Orford, K. J.; Ostrowski, M.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Ryde, F.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schück, F. M.; Schünwald, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sushch, I.; Sikora, M.; Skilton, J. L.; Sol, H.; Stawarz, L.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Venter, L.; Vialle, J. P.; Viana, A.; Vincent, P.; Vivier, M.; Vülk, H. J.; Volpe, F.; Vorobiov, S.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    We have conducted a search for the giant Pair Halo structures which are inevitably formed around TeV sources due to interactions of very high energy gamma-rays with the Extragalactic Background Light (EBL). The resulting electron/positron pairs are Compton upscattered on photons of the 2.7 K Cosmic Microwave Background Radiation to produce a second generation of gamma-rays which again interact with the EBL; thus an electromagnetic cascade develops. If the magnetic fields on Mpc scales surrounding the central source are sufficiently strong (10-11 G or more), electrons are effectively isotropised before interacting with radiation fields. In this case an extended halo is produced around the source. Using H.E.S.S. observations of Active Galactic Nuclei, including data from PKS 2155-304, 1ES 1101-232 and 1ES 0229+200, we have completed a detailed analysis of these sources. I will present and discuss the astrophysical implications of these results.

  11. Modelling Gender Pay Gaps

    OpenAIRE

    2004-01-01

    EXECUTIVE SUMMARYIntroductionThere has been little change in the full-time gender pay gap since the mid 1990s andin the female part-time/male full-time pay gap since the mid 1970s. The gender gapin hourly earnings for those employed full-time in Britain in 2003 was 18 per cent,while that between women working part-time and men working full-time was 40 percent.This research uses statistical methods to identify how much of the gender pay gap isassociated with different factors. The data set ana...

  12. Filling the Income Gap

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Income distribution has become one of the people's main concerns in China where more than 30years of reform and opening up have also resulted in an ever-expanding wealth gap.But narrowing down the rich-poor disparity will prove to be no easy task.Wei Zhong,a researcher with the Institute of Economics under the Chinese Academy of Social Sciences,elaborated on the origins and trends of China's widening income gap,and discussed solutions to curb the gap,in a recent article.Edited excerpts follow:

  13. Bridging The Inferential Gap

    Science.gov (United States)

    Stewart, Walter F.; Shah, Nirav R.; Selna, Mark J.; Paulus, Ronald A.; Walker, James M.

    2009-01-01

    Most clinical decisions involve bridging the inferential gap: Clinicians are required to “fill in” where they lack knowledge or where no knowledge yet exists. In this context we consider how the inferential gap is a product, in part, of how knowledge is created, the limits to gaining access to such knowledge, and the variable ways in which knowledge is translated into decisions. We consider how electronic health records (EHRs) will help narrow this gap by accelerating the creation of evidence relevant to everyday practice needs and facilitating real-time use of knowledge in practice. PMID:17259202

  14. Small-Gap Flows

    Science.gov (United States)

    1984-04-01

    34’OF CALIFORNIA# BERKELEY, CA 5.1720 ft (45 642-141 SMALL- GAP FLOWS BY E. 0. TUCK REPORT No. NAUE 84-1 CONTRACT N00014-84-K-OU26 APRIL i984...Mechanics, 41 (1970) 769-792. 11 3. Shallow-Water Waves at Discontinuities Shallow-water waves represent perhaps the prototype small- gap flow , the...solving (4.4) we need "initial" conditions at the starting station z = 0, and "exit" conditions at the station z = L where the gap flow merges with the

  15. Inter-organizational cooperation in community health organizations.

    Science.gov (United States)

    Franco, Mário; Haase, Heiko

    2015-01-01

    The purpose of this paper is to examine various aspects related to inter-organizational cooperation and how this phenomenon can be applied to healthcare institutions. To fulfil the aim, a qualitative investigation was adopted, focussing on the relationship between public hospital and a higher education institution in Portugal. The study supports health managers and higher education leaders, and other stakeholders involved inter-organizational cooperation drawing up strategies and understanding inter-organizational cooperation's impact at the regional level. One contribution is to help fill a gap regarding the empirical research surrounding cooperation between organizations, especially in the health sector, where scientific studies are scarce. It also provides new insights by applying competence-based theory to analyze different approaches to hospital cooperation, which has received scant attention in the health sector.

  16. Fission: statistical nucleon pair breaking

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, M. (Instituto Peruano de Energia Nuclear, Lima (Peru))

    1984-06-01

    In order to explain the odd-even effect observed in low energy fission fragment distributions it has been recently required a double mechanism of nucleon pair breaking: before scission (early pair breaking) and at scission (late pair breaking), respectively. In the present work we show that, using the same formulae but considering only the early pair breaking mechanism, one can reproduce fairly well all the available experimental data on the odd-even effects.

  17. Cellular cooperation: insights from microbes.

    Science.gov (United States)

    Celiker, Hasan; Gore, Jeff

    2013-01-01

    Cooperation between cells is a widespread phenomenon in nature, found across diverse systems ranging from microbial populations to multicellular organisms. For cooperation to evolve and be maintained within a population of cells, costs due to competition have to be outweighed by the benefits gained through cooperative actions. Because cooperation generally confers a cost to the cooperating cells, defector cells that do not cooperate but reap the benefits of cooperation can thrive and eventually drive the cooperating phenotypes to extinction. Here we summarize recent advances made in understanding how cooperation and multicellularity can evolve in microbial populations in the face of such conflicts and discuss parallels with cell populations within multicellular organisms.

  18. Diffractive charged meson pair production

    CERN Document Server

    Lehmann-Dronke, B; Schäfer, S; Stein, E; Schäfer, A

    1999-01-01

    We investigate the possibility to measure the nonforward gluon distribution function by means of diffractively produced charged pion and kaon pairs in polarized lepton nucleon scattering. The resulting cross sections are sizable and are dominated by the gluonic contribution. We find large spin asymmetries, both for pion pairs and for kaon pairs.

  19. Application of Acupoints in Pairs

    Institute of Scientific and Technical Information of China (English)

    季扬

    2004-01-01

    @@ Application of acupoints in pairs is a kind of point association in which only a pair of compatible points is used. Based on the principle of compatibility, the author of this article often uses the "pair-point needling" to treat some common diseases, and have obtained very good therapeutic results. Some examples are introduced below.

  20. Filling the Income Gap

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Income distribution has become one of the people’s main concerns in China where more than 30 years of reform and opening up have also resulted in an ever-expanding wealth gap. But narrowing down the

  1. Cotorsion Pair Extensions

    Institute of Scientific and Technical Information of China (English)

    De Xu ZHOU

    2009-01-01

    Assume that S is an almost excellent extension of R. Using functors Hom R(S,-) and -(×)R S, we establish some connections between classes of modules (L)R and (L)S, cotorsion pairs ((A)R, (A)R)and ((A)S, (B)S). If (L)S is a T-extension or (and) H-extension of (L)R, we show that (L)S is a (resp., monomorphic, epimorphic, special) preenveloping class if and only if so is (L)R. If (S, S) is a TH-extension of ((A)R,(B)R), we obtain that ((A)S,(B)S) is complete (resp., of finite type, of cofinite type, hereditary, perfect, n-tilting) if and only if so is ((A)R,(B)R).

  2. Cooperation or Silent Rivalry?

    DEFF Research Database (Denmark)

    Zank, Wolfgang

    2010-01-01

    on an increasingly institutionalized basis. In terms of military cooperation the US is still the partner for Egypt. But outside the military sphere institutionalized cooperation is comparatively week. In particular the failure of the US to conclude a free-trade agreement has been crucial. But it would be wrong...

  3. Readings in Cooperative Education.

    Science.gov (United States)

    Leventhal, Jerome I.

    Twenty-three journal articles on cooperative education were selected in a review of the literature by two Temple University graduate classes in the fall of 1975 and the spring of 1976 for those interested in the role of coordinating cooperative education programs. The journal readings consist of articles on theory/planning (6), implementation…

  4. Coordination and Cooperation

    OpenAIRE

    Janssen, Maarten

    2003-01-01

    textabstractThis comment makes four related points. First, explaining coordination is different from explaining cooperation. Second, solving the coordination problem is more important for the theory of games than solving the cooperation problem. Third, a version of the Principle of Coordination can be rationalized on individualistic grounds. Finally, psychological game theory should consider how players perceive their gaming situation. ---------------------------------------------------------...

  5. Cooperation, compensation and transition

    NARCIS (Netherlands)

    Ju, Y.

    2004-01-01

    Cooperation and compensation are two important and well-linked issues in economics. The central question in cooperation is how to share the joint gains among participating players. Compensation is a specific aspect of surplus sharing problems providing incentives for agents to sacrifice their own di

  6. Cooperative Science Lesson Plans.

    Science.gov (United States)

    Cooperative Learning, 1991

    1991-01-01

    Offers several elementary level cooperative science lesson plans. The article includes a recipe for cooperative class learning, instructions for making a compost pile, directions for finding evidence of energy, experiments in math and science using oranges to test density, and discussions of buoyancy using eggs. (SM)

  7. Cooperative Learning Strategies.

    Science.gov (United States)

    Barnes, Buckley; O'Farrell, Gail

    1990-01-01

    Presents essential characteristics and types of cooperative learning strategies for use in elementary social studies. Outlines exercises for forming teams and building team spirit. Points out such methods promote group interdependence and student responsibility for learning and teaching others. Highlights two cooperative group strategies, Jigsaw…

  8. Coordination and Cooperation

    NARCIS (Netherlands)

    M.C.W. Janssen (Maarten)

    2003-01-01

    textabstractThis comment makes four related points. First, explaining coordination is different from explaining cooperation. Second, solving the coordination problem is more important for the theory of games than solving the cooperation problem. Third, a version of the Principle of Coordination can

  9. International Cooperation Advances Internationalization

    Institute of Scientific and Technical Information of China (English)

    Ge Mingyi

    2004-01-01

    @@ Intemational scientific cooperation continues to successfully promote the development of research and the quality of researchers in China, and also the internationalization of China's research system and research organizations. An outstanding example of this is the 30 years of fruitful cooperation between the Chinese Academy of Sciences and the Max Planck Society.

  10. Coordination and Cooperation

    NARCIS (Netherlands)

    M.C.W. Janssen (Maarten)

    2003-01-01

    textabstractThis comment makes four related points. First, explaining coordination is different from explaining cooperation. Second, solving the coordination problem is more important for the theory of games than solving the cooperation problem. Third, a version of the Principle of Coordination can

  11. The Effects of a Roommate-Pairing Program on International Student Satisfaction and Academic Success

    Science.gov (United States)

    Tolman, Steven

    2017-01-01

    While great attention has been given to the growth of international students at U.S. institutions, there is a gap in the literature examining support for this student population within residence halls. To address the gap, this quantitative study evaluated an international roommate-pairing program (IRP) by comparing the residential experience of…

  12. Partner Choice Drives the Evolution of Cooperation via Indirect Reciprocity.

    Directory of Open Access Journals (Sweden)

    Gilbert Roberts

    Full Text Available Indirect reciprocity potentially provides an important means for generating cooperation based on helping those who help others. However, the use of 'image scores' to summarize individuals' past behaviour presents a dilemma: individuals withholding help from those of low image score harm their own reputation, yet giving to defectors erodes cooperation. Explaining how indirect reciprocity could evolve has therefore remained problematic. In all previous treatments of indirect reciprocity, individuals are assigned potential recipients and decide whether to cooperate or defect based on their reputation. A second way of achieving discrimination is through partner choice, which should enable individuals to avoid defectors. Here, I develop a model in which individuals choose to donate to anyone within their group, or to none. Whereas image scoring with random pairing produces cycles of cooperation and defection, with partner choice there is almost maximal cooperation. In contrast to image scoring with random pairing, partner choice results in almost perfect contingency, producing the correlation between giving and receiving required for cooperation. In this way, partner choice facilitates much higher and more stable levels of cooperation through image scoring than previously reported and provides a simple mechanism through which systems of helping those who help others can work.

  13. Efficiency in Microfinance Cooperatives

    Directory of Open Access Journals (Sweden)

    HARTARSKA, Valentina

    2012-12-01

    Full Text Available In recognition of cooperatives’ contribution to the socio-economic well-being of their participants, the United Nations has declared 2012 as the International Year of Cooperatives. Microfinance cooperatives make a large part of the microfinance industry. We study efficiency of microfinance cooperatives and provide estimates of the optimal size of such organizations. We employ the classical efficiency analysis consisting of estimating a system of equations and identify the optimal size of microfinance cooperatives in terms of their number of clients (outreach efficiency, as well as dollar value of lending and deposits (sustainability. We find that microfinance cooperatives have increasing returns to scale which means that the vast majority can lower cost if they become larger. We calculate that the optimal size is around $100 million in lending and half of that in deposits. We find less robust estimates in terms of reaching many clients with a range from 40,000 to 180,000 borrowers.

  14. Culture and cooperation.

    Science.gov (United States)

    Gächter, Simon; Herrmann, Benedikt; Thöni, Christian

    2010-09-12

    Does the cultural background influence the success with which genetically unrelated individuals cooperate in social dilemma situations? In this paper, we provide an answer by analysing the data of Herrmann et al. (2008a), who studied cooperation and punishment in 16 subject pools from six different world cultures (as classified by Inglehart & Baker (2000)). We use analysis of variance to disentangle the importance of cultural background relative to individual heterogeneity and group-level differences in cooperation. We find that culture has a substantial influence on the extent of cooperation, in addition to individual heterogeneity and group-level differences identified by previous research. The significance of this result is that cultural background has a substantial influence on cooperation in otherwise identical environments. This is particularly true in the presence of punishment opportunities.

  15. The Binding Energy, Spin-Excitation Gap, and Charged Gap in the Boson-Fermion Model

    Institute of Scientific and Technical Information of China (English)

    YANG Kai-Hua; TIAN Guang-Shan; HAN Ru-Qi

    2003-01-01

    In this paper, by applying a simplified version of Lieb 's spin-refleetion-positivity method, which was recentlydeveloped by one of us [G.S. Tian and J.G. Wang, J. Phys. A: Math. Gen. 35 (2002) 941], we investigate some generalproperties of the boson-fermion Hamiltonian, which has been widely used as a phenomenological model to describe thereal-space pairing of electrons. On a mathematically rigorous basis, we prove that for either negative or positive couplingV, which represents the spontaneous decay and recombination process between boson and fermion in the model, thepairing energy of electrons is nonzero. Furthermore, we also show that the spin-excitation gap of the boson-fermionHamiltonian is always larger than its charged gap, as predicted by the pre-paired electron theory.

  16. The Binding Energy, Spin-Excitation Gap, and Charged Gap in the Boson-Fermion Model

    Institute of Scientific and Technical Information of China (English)

    YANGKai-Hua; Guang-Shan; HANRu-Qi

    2003-01-01

    In this paper, by applying a simplified version of Lieb's spin-reflection-positivity method, which was recently developed by one of us [G.S. Tian and J.G. Wang, J. Phys. A: Math. Gen. 35 (2002) 941], we investigate some general properties of the boeon-fermion Hamiltonlan, which has been widely used as a phenomenological model to describe the real-space pairing of electrons. On a mathematically rigorous basis, we prove that for either negative or positive couping V, which represents the spontaneous decay and recombination process between boson and fermion in the model, the pairing energy of electrons is nonzero. Furthermore, we also show that the spin-excitation gap of the boson-fermion Hamiltonian is always larger than its charged gap, as predicted by the pre-palred electron theory.

  17. Fluid-dynamical description of the gap fluctuations of two trapped fermion species

    Science.gov (United States)

    Capuzzi, P.; Hernández, E. S.; Szybisz, L.

    2010-11-01

    We apply a recent generalisation of the fluid-dynamical scheme developed for two trapped fermion species with pairing interactions to examine the fluctuations of the gap density coupled to the particle transition density at low energy. The dynamical scheme satisfies Kohn's theorem for both the particle density and the pairing gap. We analyse the form of the gap fluctuations in a spherical trap in terms of their multipolarity and the interaction strength, and find that coupling to the particle density produces considerable stiffness of the gap transition density together with compression towards the centre of the trap.

  18. Multi-pair states in electron–positron pair creation

    Directory of Open Access Journals (Sweden)

    Anton Wöllert

    2016-09-01

    Full Text Available Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron–positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron–positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron–positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron–positron pairs.

  19. GAP Land Cover - Vector

    Data.gov (United States)

    Minnesota Department of Natural Resources — This vector dataset is a detailed (1-acre minimum), hierarchically organized vegetation cover map produced by computer classification of combined two-season pairs of...

  20. Experimental many-pairs nonlocality

    Science.gov (United States)

    Poh, Hou Shun; Cerè, Alessandro; Bancal, Jean-Daniel; Cai, Yu; Sangouard, Nicolas; Scarani, Valerio; Kurtsiefer, Christian

    2017-08-01

    Collective measurements on large quantum systems together with a majority voting strategy can lead to a violation of the Clauser-Horne-Shimony-Holt Bell inequality. In the presence of many entangled pairs, this violation decreases quickly with the number of pairs and vanishes for some critical pair number that is a function of the noise present in the system. Here we show that a different binning strategy can lead to a more substantial Bell violation when the noise is sufficiently small. Given the relation between the critical pair number and the source noise, we then present an experiment where the critical pair number is used to quantify the quality of a high visibility photon pair source. Our results demonstrate nonlocal correlations using collective measurements operating on clusters of more than 40 photon pairs.

  1. Exact and approximate ensemble treatments of thermal pairing in a multilevel model

    Science.gov (United States)

    Hung, N. Quang; Dang, N. Dinh

    2009-05-01

    A systematic comparison is conducted for pairing properties of finite systems at nonzero temperature as predicted by the exact solutions of the pairing problem embedded in three principal statistical ensembles, as well as the unprojected (FTBCS1+SCQRPA) and Lipkin+Nogami projected (FTLN1+SCQRPA) theories that include the quasiparticle number fluctuation and coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The numerical calculations are performed for the pairing gap, total energy, heat capacity, entropy, and microcanonical temperature within the doubly folded equidistant multilevel pairing model. The FTLN1+SCQRPA predictions agree best with the exact grand-canonical results. In general, all approaches clearly show that the superfluid-normal phase transition is smoothed out in finite systems. A novel formula is suggested for extracting the empirical pairing gap in reasonable agreement with the exact canonical results.

  2. Exact and approximate ensemble treatments of thermal pairing in a multilevel model

    CERN Document Server

    Hung, N Quang

    2009-01-01

    A systematic comparison is conducted for pairing properties of finite systems at nonzero temperature as predicted by the exact solutions of the pairing problem embedded in three principal statistical ensembles, as well as the unprojected (FTBCS1+SCQRPA) and Lipkin-Nogami projected (FTLN1+SCQRPA) theories that include the quasiparticle number fluctuation and coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The numerical calculations are performed for the pairing gap, total energy, heat capacity, entropy, and microcanonical temperature within the doubly-folded equidistant multilevel pairing model. The FTLN1+SCQRPA predictions agree best with the exact grand-canonical results. In general, all approaches clearly show that the superfluid-normal phase transition is smoothed out in finite systems. A novel formula is suggested for extracting the empirical pairing gap in reasonable agreement with the exact canonical results.

  3. Cobreeding in the burying beetle, Nicrophorus vespilloides : Tolerance rather than cooperation

    NARCIS (Netherlands)

    Komdeur, Jan; Schrama, Maarten J. J.; Meijer, Kim; Moore, Allen J.; Beukeboom, Leo W.

    2013-01-01

    Under intra- and interspecific competition, cooperative behaviour can provide direct fitness benefits if individuals work together to expel intruders. In the burying beetle Nicrophorus vespilloides, a relatively small species, multiple unrelated pairs can breed together, and individuals are weak com

  4. Microwave Type III Pair Bursts in Solar Flares

    CERN Document Server

    Tan, Baolin; Karlicky, Marian; Huang, Guangli; Tan, Chengming

    2016-01-01

    Solar microwave type III pair burst is composed of normal and reverse-sloped (RS) burst branches with oppositely fast frequency drifts. It is the most sensitive signature of the primary energy release and electron accelerations in flares. This work reported 11 microwave type III pair events in 9 flares observed by radio spectrometers in China and the Czech Republic at frequency of 0.80 - 7.60 GHz during 1994 - 2014. These type III pairs occurred in flare impulsive and postflare phases with separate frequency in range of 1.08 - 3.42 GHz and frequency gap 10 - 1700 MHz. The frequency drift increases with the separate frequency (f_{x}), the lifetime of each burst is anti-correlated to f_{x}, while the frequency gap is independent to f_{x}. In most events, the normal branches are drifting obviously faster than the RS branches. The type III pairs occurring in flare impulsive phase have lower separate frequency, longer lifetime, wider frequency gap, and slower frequency drift than that occurring in postflare phase....

  5. Development of cooperative system bridges

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhe; WAN Qi-bai; SHI Lei

    2008-01-01

    Cooperative system bridges comprise several basic structures that act jointly to improve structural characteristics. We delved into the historical development of cooperative system bridges. Cooperative systems are classified as different-load cooperative systems and same-load cooperative systems by distinguishing the modes of load distribution. For different-load cooperation, individual basic structures are at different positions in the direction along bridge axis and carry the loads separately. While for same-load cooperation, all basic structures overlap in geometrical locations and support the entire loads conjointly. The choosing of span ratios between basic structures, the design of connections of different-load cooperative systems were discussed as well as optimizations of relative rigidity for same-load cooperative systems which greatly influence structural characteristics. The general situation and several structural measurements of several cooperative bridges were demonstrated. This information can assist engineers in developing their concepts in cooperative systems and can lead to more efficient and economical cooperative bridges.

  6. Superdeformed rotational bands with density dependent pairing interactions

    Energy Technology Data Exchange (ETDEWEB)

    Terasaki, J. [Service de Physique Nucleaire Theorique, Brussels (Belgium); Heenen, P.H. [Service de Physique Nucleaire Theorique, Brussels (Belgium); Bonche, P. [SPhT - CE Saclay, 91191 Gif-sur-Yvette Cedex (France); Dobaczewski, J. [Institute of Theoretical Physics, Warsaw University, Hoza 69, PL-00-681 Warsaw (Poland); Flocard, H. [Division de Physique Theorique, Institut de Physique Nucleaire, 91406 Orsay Cedex (France)

    1995-10-09

    The cranked Hartree-Fock-Bogoliubov method, applied in a previous study to SD bands of even Hg and Pb isotopes, is extended by including pairing correlations described by a zero-range density-dependent interaction. This more realistic description of the pairing channel modifies the balance between the neutron and proton pairing energies and introduces an orbital variation of the pairing gaps. This results in a retarded alignment, significantly improving the agreement with data in both the A=150 and 190 mass regions. The behavior expected for SD bands in odd-N or odd-Z nuclei is discussed on the basis of the quasiparticle routhians calculated for the even-even isotopes. (orig.).

  7. Superdeformed rotational bands with density dependent pairing interactions

    Science.gov (United States)

    Terasaki, J.; Heenen, P.-H.; Bonche, P.; Dobaczewski, J.; Flocard, H.

    1995-02-01

    The cranked Hartree-Fock-Bogoliubov method, applied in a previous study to SD bands of even Hg and Pb isotopes, is extended by including pairing correlations described by a zero-range density-dependent interaction. This more realistic description of the pairing channel modifies the balance between the neutron and proton pairing energies and introduces an orbital variation of the pairing gaps. This results in a retarded alignment, significantly improving the agreement with data in both the A = 150 and 190 mass regions. The behavior expected for SD bands in odd- N or odd- Z nuclei is discussed on the basis of the quasiparticle routhians calculated for the even-even isotopes.

  8. Cooperative adaptive cruise control: An artificial potential field approach

    NARCIS (Netherlands)

    Semsar-Kazerooni, E.; Verhaegh, J.; Ploeg, J.; Alirezaei, M.

    2016-01-01

    In this paper, in addition to the main functionality of vehicle following, cooperative adaptive cruise control (CACC) is enabled with additional features of gap closing and collision avoidance. Due to its nonlinear nature, a control objective such as collision avoidance, cannot be addressed using a

  9. Cooperating Teachers' Roles and Responsibilities in a MATESOL Practicum

    Science.gov (United States)

    Payant, Caroline; Murphy, John

    2012-01-01

    Responding to a gap in relevant literatures, this study explores cooperating teachers' perceptions of their roles and responsibilities as contributors to the practicum experiences of preservice teachers of English as a second language who were pursuing a master's degree. Research tools featured focus group and individual interviews with 11…

  10. Anisotropic evolution of energy gap in Bi2212 superconductor

    Science.gov (United States)

    Durajski, A. P.

    2016-10-01

    We present a systematic analysis of the energy gap in underdoped Bi2212 superconductor as a function of temperature and hole doping level. Within the framework of the theoretical model containing the electron-phonon and electron-electron-phonon pairing mechanism, we reproduced the measurement results of modern ARPES experiments with very high accuracy. We showed that the energy-gap amplitude is very weakly dependent on the temperature but clearly dependent on the level of doping. The evidence for a non-zero energy gap above the critical temperature, referred to as a pseudogap, was also obtained.

  11. Cooperation is related to dispersal patterns in Sino-Tibetan populations

    Science.gov (United States)

    Wu, Jia-Jia; Ji, Ting; He, Qiao-Qiao; Du, Juan; Mace, Ruth

    2015-01-01

    There is growing recognition in both evolutionary biology and anthropology that dispersal is key to establishing patterns of cooperation. However, some models predict that cooperation is more likely to evolve in low dispersal (viscous) populations, while others predict that local competition for resources inhibits cooperation. Sex-biased dispersal and extra-pair mating may also have an effect. Using economic games in Sino-Tibetan populations with strikingly different dispersal patterns, we measure cooperation in 36 villages in southwestern China; we test whether social structure is associated with cooperative behaviour toward those in the neighbourhood. We find that social organization is associated with levels of cooperation in public goods and dictator games and a resource dilemma; people are less cooperative towards other villagers in communities where dispersal by both sexes is low. This supports the view that dispersal for marriage played an important role in the evolution of large-scale cooperation in human society. PMID:26478534

  12. Network modularity promotes cooperation.

    Science.gov (United States)

    Marcoux, Marianne; Lusseau, David

    2013-05-01

    Cooperation in animals and humans is widely observed even if evolutionary biology theories predict the evolution of selfish individuals. Previous game theory models have shown that cooperation can evolve when the game takes place in a structured population such as a social network because it limits interactions between individuals. Modularity, the natural division of a network into groups, is a key characteristic of all social networks but the influence of this crucial social feature on the evolution of cooperation has never been investigated. Here, we provide novel pieces of evidence that network modularity promotes the evolution of cooperation in 2-person prisoner's dilemma games. By simulating games on social networks of different structures, we show that modularity shapes interactions between individuals favouring the evolution of cooperation. Modularity provides a simple mechanism for the evolution of cooperation without having to invoke complicated mechanisms such as reputation or punishment, or requiring genetic similarity among individuals. Thus, cooperation can evolve over wider social contexts than previously reported.

  13. Globalization and human cooperation.

    Science.gov (United States)

    Buchan, Nancy R; Grimalda, Gianluca; Wilson, Rick; Brewer, Marilynn; Fatas, Enrique; Foddy, Margaret

    2009-03-17

    Globalization magnifies the problems that affect all people and that require large-scale human cooperation, for example, the overharvesting of natural resources and human-induced global warming. However, what does globalization imply for the cooperation needed to address such global social dilemmas? Two competing hypotheses are offered. One hypothesis is that globalization prompts reactionary movements that reinforce parochial distinctions among people. Large-scale cooperation then focuses on favoring one's own ethnic, racial, or language group. The alternative hypothesis suggests that globalization strengthens cosmopolitan attitudes by weakening the relevance of ethnicity, locality, or nationhood as sources of identification. In essence, globalization, the increasing interconnectedness of people worldwide, broadens the group boundaries within which individuals perceive they belong. We test these hypotheses by measuring globalization at both the country and individual levels and analyzing the relationship between globalization and individual cooperation with distal others in multilevel sequential cooperation experiments in which players can contribute to individual, local, and/or global accounts. Our samples were drawn from the general populations of the United States, Italy, Russia, Argentina, South Africa, and Iran. We find that as country and individual levels of globalization increase, so too does individual cooperation at the global level vis-à-vis the local level. In essence, "globalized" individuals draw broader group boundaries than others, eschewing parochial motivations in favor of cosmopolitan ones. Globalization may thus be fundamental in shaping contemporary large-scale cooperation and may be a positive force toward the provision of global public goods.

  14. Pairing the Volcano

    CERN Document Server

    Ionica, Sorina

    2011-01-01

    Isogeny volcanoes are graphs whose vertices are elliptic curves and whose edges are $\\ell$-isogenies. Algorithms allowing to travel on these graphs were developed by Kohel in his thesis (1996) and later on, by Fouquet and Morain (2001). However, up to now, no method was known, to predict, before taking a step on the volcano, the direction of this step. Hence, in Kohel's and Fouquet-Morain algorithms, many steps are taken before choosing the right direction. In particular, ascending or horizontal isogenies are usually found using a trial-and-error approach. In this paper, we propose an alternative method that efficiently finds all points $P$ of order $\\ell$ such that the subgroup generated by $P$ is the kernel of an horizontal or an ascending isogeny. In many cases, our method is faster than previous methods. This is an extended version of a paper published in the proceedings of ANTS 2010. In addition, we treat the case of 2-isogeny volcanoes and we derive from the group structure of the curve and the pairing ...

  15. Mind the Gap

    Science.gov (United States)

    Schuller, Tom

    2007-01-01

    One of the most striking, and almost universal, educational trends of the last decade has been the shift in the relative achievements of males and females. In almost every OECD (Organisation for Economic Cooperation and Development) country, girls now do better than boys at almost every level, up to and including doctoral, and in almost every…

  16. Broadband illumination of superconducting pair breaking photon detectors

    Science.gov (United States)

    Guruswamy, T.; Goldie, D. J.; Withington, S.

    2016-04-01

    Understanding the detailed behaviour of superconducting pair breaking photon detectors such as Kinetic Inductance Detectors (KIDs) requires knowledge of the nonequilibrium quasiparticle energy distributions. We have previously calculated the steady state distributions resulting from uniform absorption of monochromatic sub gap and above gap frequency radiation by thin films. In this work, we use the same methods to calculate the effect of illumination by broadband sources, such as thermal radiation from astrophysical phenomena or from the readout system. Absorption of photons at multiple above gap frequencies is shown to leave unchanged the structure of the quasiparticle energy distribution close to the superconducting gap. Hence for typical absorbed powers, we find the effects of absorption of broadband pair breaking radiation can simply be considered as the sum of the effects of absorption of many monochromatic sources. Distribution averaged quantities, like quasiparticle generation efficiency η, match exactly a weighted average over the bandwidth of the source of calculations assuming a monochromatic source. For sub gap frequencies, however, distributing the absorbed power across multiple frequencies does change the low energy quasiparticle distribution. For moderate and high absorbed powers, this results in a significantly larger η-a higher number of excess quasiparticles for a broadband source compared to a monochromatic source of equal total absorbed power. Typically in KIDs the microwave power absorbed has a very narrow bandwidth, but in devices with broad resonance characteristics (low quality factors), this increase in η may be measurable.

  17. Scandinavian Cooperative Advantage

    DEFF Research Database (Denmark)

    Strand, Robert; Freeman, R. Edward

    2015-01-01

    . We conclude by endorsing the expression “Scandinavian cooperative advantage” in an effort to draw attention to the Scandinavian context and encourage the field of strategic management to shift its focus from achieving a competitive advantage toward achieving a cooperative advantage....... of relationships to these historical contributions. Thus, we propose that Scandinavia offers a particularly promising context from which to draw inspiration regarding effective company-stakeholder cooperation and where ample of examples of what is more recently referred to as “creating shared value” can be found...

  18. Semantic Gaps Are Dangerous

    DEFF Research Database (Denmark)

    Ejstrup, Michael; le Fevre Jakobsen, Bjarne

    Semantic gaps are dangerous Language adapts to the environment where it serves as a tool to communication. Language is a social agreement, and we all have to stick to both grammaticalized and non-grammaticalized rules in order to pass information about the world around us. As such language develops...... unpolite language and tend to create dangerous relations where specialy language creates problems and trouble that could be avoided if we had better language tools at hand. But we have not these tools of communication, and we are in a situation today where media and specially digital and social media......, supported by new possibilities of migration, create dangerous situations. How can we avoid these accidental gaps in language and specially the gaps in semantic and metaphoric tools. Do we have to keep silent and stop discusing certain isues, or do we have other ways to get acces to sufficient language tools...

  19. Gap Cycling for SWIFT

    CERN Document Server

    Corum, Curtis A; Snyder, Carl J; Garwood, Michael

    2013-01-01

    Purpose: SWIFT (SWeep Imaging with Fourier Transformation) is a non- Cartesian MRI method with unique features and capabilities. In SWIFT, radiofrequency (RF) excitation and reception are performed nearly simultaneously, by rapidly switching between transmit and receive during a frequency-swept RF pulse. Because both the transmitted pulse and data acquisition are simultaneously amplitude-modulated in SWIFT (in contrast to continuous RF excitation and uninterrupted data acquisition in more familiar MRI sequences), crosstalk between different frequency bands occurs in the data. This crosstalk leads to a "bulls-eye" artifact in SWIFT images. We present a method to cancel this inter-band crosstalk by cycling the pulse and receive gap positions relative to the un-gapped pulse shape. We call this strategy "gap cycling." Methods: We carry out theoretical analysis, simulation and experiments to characterize the signal chain, resulting artifacts, and their elimination for SWIFT. Results: Theoretical analysis reveals t...

  20. Missing the gap

    DEFF Research Database (Denmark)

    Tanggaard, Lene; Glaveanu, Vlad Petre

    creative learning at the borders need not minimize differences, but handle and learn from them? If not, schools and educational institutions risk becoming bad copies of the labour marked instead of enabling students to enter the market with something new, something radically dissimilar from what......Missing the gap This paper is focused on an exploration of creative learning involved in boundary crossing (Tanggaard, 2007). Our aim is to explore the trajectories and pathways realised by students as they move from education to work and vice versa (Tanggaard & Beghetto, 2015), guided...... by the premise that difference and gaps are places where creative learning is intensified (Glaveanu & Gillespie, 2015). The public discourse around education is often concerned with minding or avoiding the gap by making education more relevant for or similar to the labour market, but what if facilitating...

  1. Multiple origins of asteroid pairs

    CERN Document Server

    Jacobson, Seth A

    2015-01-01

    Rotationally fissioned asteroids produce unbound daughter asteroids that have very similar heliocentric orbits. Backward integration of their current heliocentric orbits provides an age of closest proximity that can be used to date the rotational fission event. Most asteroid pairs follow a predicted theoretical relationship between the primary spin period and the mass ratio of the two pair members that is a direct consequence of the YORP-induced rotational fission hypothesis. If the progenitor asteroid has strength, asteroid pairs may have high mass ratios with possibly fast rotating primaries. However, secondary fission leaves the originally predicted trend unaltered. We also describe the characteristics of pair members produced by four alternative routes from a rotational fission event to an asteroid pair. Unlike direct formation from the event itself, the age of closest proximity of these pairs cannot generally be used to date the rotational fission event since considerable time may have passed.

  2. The longevity gender gap

    DEFF Research Database (Denmark)

    Aviv, Abraham; Shay, Jerry; Christensen, Kaare

    2005-01-01

    In this Perspective, we focus on the greater longevity of women as compared with men. We propose that, like aging itself, the longevity gender gap is exceedingly complex and argue that it may arise from sex-related hormonal differences and from somatic cell selection that favors cells more...... resistant to the ravages of time. We discuss the interplay of these factors with telomere biology and oxidative stress and suggest that an explanation for the longevity gender gap may arise from a better understanding of the differences in telomere dynamics between men and women....

  3. Cooperative processing data bases

    Science.gov (United States)

    Hasta, Juzar

    1991-01-01

    Cooperative processing for the 1990's using client-server technology is addressed. The main theme is concepts of downsizing from mainframes and minicomputers to workstations on a local area network (LAN). This document is presented in view graph form.

  4. Cooperative Hurricane Network Obs

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Observations from the Cooperative Hurricane Reporting Network (CHURN), a special network of stations that provided observations when tropical cyclones approached the...

  5. Cooperative Transport Planning

    NARCIS (Netherlands)

    Zutt, J.; De Weerdt, M.M.

    2000-01-01

    To test and compare different forms of cooperative planning algorithms developed in the CABS project we use a generic simulator called MARS. Examples in the transportation sector are implemented in this simulator.

  6. Solar cooperatives; Genosse Sonne

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Dierk

    2010-06-15

    Not a boom but a trend: Increasingly, solar power plants and other renewables-based systems are financed by cooperatives. This organizational structure requires long-term strategies and some idealism. (orig.)

  7. Cooperative Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly logs include a daily account of temperature extremes and precipitation, along with snow data at some locations. U.S. Cooperative Observer Program (COOP)...

  8. Cooperative Bacterial Foraging Optimization

    Directory of Open Access Journals (Sweden)

    Hanning Chen

    2009-01-01

    Full Text Available Bacterial Foraging Optimization (BFO is a novel optimization algorithm based on the social foraging behavior of E. coli bacteria. This paper presents a variation on the original BFO algorithm, namely, the Cooperative Bacterial Foraging Optimization (CBFO, which significantly improve the original BFO in solving complex optimization problems. This significant improvement is achieved by applying two cooperative approaches to the original BFO, namely, the serial heterogeneous cooperation on the implicit space decomposition level and the serial heterogeneous cooperation on the hybrid space decomposition level. The experiments compare the performance of two CBFO variants with the original BFO, the standard PSO and a real-coded GA on four widely used benchmark functions. The new method shows a marked improvement in performance over the original BFO and appears to be comparable with the PSO and GA.

  9. Landscape Conservation Cooperatives

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Landscape Conservation Cooperatives (LCCs) are public-private partnerships composed of states, tribes, federal agencies, non-governmental organizations,...

  10. Regional National Cooperative Observer

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA publication dedicated to issues, news and recognition of observers in the National Weather Service Cooperative Observer program. Issues published regionally...

  11. Globalization and economic cooperation

    Directory of Open Access Journals (Sweden)

    Javier Divar

    2006-12-01

    Full Text Available Economic globalization is nothing, really, that the universality of capitalism. Not globalized culture, and economic participation, and human rights, ... has only globalized market. We must react by substituting those materialistic values with cooperative economy.

  12. Cooperative Purchasing Reduces Costs.

    Science.gov (United States)

    Kula, Edwin J.

    1981-01-01

    Several suburban Chicago (Illinois) school districts are members of the South Suburban School Purchasing Cooperative, which serves as a conduit for volume purchases of educational supplies. (Author/MLF)

  13. Cooperating and Prospering

    Institute of Scientific and Technical Information of China (English)

    ZHAO MINGWEN

    2010-01-01

    @@ Since its establish-ment in 2001, the Shanghai Cooperation Organization (SCO)-a re-gional organization grouping China, Russia, Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan-has grown at a notable pace.

  14. Cooperative Fire Protection Agreement

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this Agreement is to provide for cooperation in the prevention, detection and suppression of wildland fires within the protection areas designated in...

  15. Cooperation Beats Conflict

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China and the Philippines agree to strengthen economic and trade cooperation while minimizing disputes Philippine President Benigno Aquino III recently completed a five-day visit to China, his first state visit to China since he took office last year.

  16. On Optimal Policies for Network-Coded Cooperation

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Roetter, Daniel Enrique Lucani; Pahlevani, Peyman

    2015-01-01

    's Raspberry Pi testbed and compared with random linear network coding (RLNC) broadcast in terms of completion time, total number of required transmissions, and percentage of delivered generations. Our measurements show that enabling cooperation only among pairs of devices can decrease the completion time...

  17. The Evolution and Ecology of Cooperative Breeding in Vertebrates

    NARCIS (Netherlands)

    Komdeur, Jan; Eikenaar, Cas; Brouwer, Lyanne; Richardson, David S.

    2008-01-01

    Cooperative breeding – in which some adults forgo independent breeding and remain as subordinates within a group helping to raise the offspring of others – occurs in between 3% and 10% of vertebrates. The structure of such systems varies greatly, from pairs with helpers-at-the-nest to communal breed

  18. Cooperating mobile robots

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, John J.; Eskridge, Steven E.; Hurtado, John E.; Byrne, Raymond H.

    2004-02-03

    A miniature mobile robot provides a relatively inexpensive mobile robot. A mobile robot for searching an area provides a way for multiple mobile robots in cooperating teams. A robotic system with a team of mobile robots communicating information among each other provides a way to locate a source in cooperation. A mobile robot with a sensor, a communication system, and a processor, provides a way to execute a strategy for searching an area.

  19. Extending Eurasia Security Cooperation

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    After 14 years of development, the Shanghai Cooperation Organization (SCO) , has set its sights on goals for the next de-cade at the 15th meeting of the Council of SCO Heads of State that was held in Ufa, the capital of Russia's Bashkortostan Republic, on July 9-10. The SCO, established in Shanghai in 2001, is committed to building fdendly neighbor rela- tions and maintaining security and stability in the Central Asian region through multilateral cooperation.

  20. Cooperation Without Intervention

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In January, China announced its desire to increase cooperation with African countries by issuing China's African Policy, a paper intended to guide relations with the continent by continuing a non-interventionist and non-ideological strategy. Christopher Mutsvangwa, Zimbabwean Ambassador to China, shared his views of the policy with Beijing Review reporter Ni Yanshuo and answered criticisms of the China-Africa relationship by Western countries that tie cooperation to democracy and human rights.

  1. Cooperation in Construction:

    DEFF Research Database (Denmark)

    Vogelius, Peter; Storgaard, Kresten

    2016-01-01

    The study presents a building project executed by a major Danish construction company, where cooperation and its staging were essential for achieving high productivity and competitiveness. The form of this cooperation is the main theme for the article. The contractor actively changed....... The management logic of the main contractor is interpreted as based on a sociology-inspired understanding focusing on norms and social values rather than on contractual (law) and functional (engineering) logic, which had hitherto been prevalent in Danish construction management....

  2. Global Reserve Cooperation

    Science.gov (United States)

    2011-03-24

    St ra te gy R es ea rc h Pr oj ec t GLOBAL RESERVE COOPERATION BY LIEUTENANT COLONEL PAMELA L. MCGAHA United States Army National Guard...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Global Reserve Cooperation 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...decade, the United States, its allies, and partner nations have greatly increased their reliance on Reserve Component forces. This global

  3. Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems† †Electronic supplementary information (ESI) available: Singlet–triplet energy gaps for CASSCF(4,4), CASSCF(8,8), DFP-1, DFP-3, and KS-DFT methods, numbers of CSFs with more significant figures, occupation numbers for HONO–1, HONO, LUNO and LUNO+1 for FP-1 and DFP-1, singlet–triplet energy gap (kcal mol–1) of decacene for DFP-1 partition with other geometries, singlet–triplet energy gap (kcal mol–1) of hexacene for different on-top functionals, molecular geometries, and absolute energies. See DOI: 10.1039/c6sc05036k Click here for additional data file.

    Science.gov (United States)

    Ghosh, Soumen

    2017-01-01

    Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e., systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. We recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functional theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet–triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet–triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data. PMID:28553509

  4. Investigating Cooperative Behavior in Ecological Settings: An EEG Hyperscanning Study

    Science.gov (United States)

    Petti, Manuela; He, Eric J.; De Giusti, Vittorio; He, Bin; Astolfi, Laura; Babiloni, Fabio

    2016-01-01

    The coordinated interactions between individuals are fundamental for the success of the activities in some professional categories. We reported on brain-to-brain cooperative interactions between civil pilots during a simulated flight. We demonstrated for the first time how the combination of neuroelectrical hyperscanning and intersubject connectivity could provide indicators sensitive to the humans’ degree of synchronization under a highly demanding task performed in an ecological environment. Our results showed how intersubject connectivity was able to i) characterize the degree of cooperation between pilots in different phases of the flight, and ii) to highlight the role of specific brain macro areas in cooperative behavior. During the most cooperative flight phases pilots showed, in fact, dense patterns of interbrain connectivity, mainly linking frontal and parietal brain areas. On the contrary, the amount of interbrain connections went close to zero in the non-cooperative phase. The reliability of the interbrain connectivity patterns was verified by means of a baseline condition represented by formal couples, i.e. pilots paired offline for the connectivity analysis but not simultaneously recorded during the flight. Interbrain density was, in fact, significantly higher in real couples with respect to formal couples in the cooperative flight phases. All the achieved results demonstrated how the description of brain networks at the basis of cooperation could effectively benefit from a hyperscanning approach. Interbrain connectivity was, in fact, more informative in the investigation of cooperative behavior with respect to established EEG signal processing methodologies applied at a single subject level. PMID:27124558

  5. Investigating Cooperative Behavior in Ecological Settings: An EEG Hyperscanning Study.

    Science.gov (United States)

    Toppi, Jlenia; Borghini, Gianluca; Petti, Manuela; He, Eric J; De Giusti, Vittorio; He, Bin; Astolfi, Laura; Babiloni, Fabio

    2016-01-01

    The coordinated interactions between individuals are fundamental for the success of the activities in some professional categories. We reported on brain-to-brain cooperative interactions between civil pilots during a simulated flight. We demonstrated for the first time how the combination of neuroelectrical hyperscanning and intersubject connectivity could provide indicators sensitive to the humans' degree of synchronization under a highly demanding task performed in an ecological environment. Our results showed how intersubject connectivity was able to i) characterize the degree of cooperation between pilots in different phases of the flight, and ii) to highlight the role of specific brain macro areas in cooperative behavior. During the most cooperative flight phases pilots showed, in fact, dense patterns of interbrain connectivity, mainly linking frontal and parietal brain areas. On the contrary, the amount of interbrain connections went close to zero in the non-cooperative phase. The reliability of the interbrain connectivity patterns was verified by means of a baseline condition represented by formal couples, i.e. pilots paired offline for the connectivity analysis but not simultaneously recorded during the flight. Interbrain density was, in fact, significantly higher in real couples with respect to formal couples in the cooperative flight phases. All the achieved results demonstrated how the description of brain networks at the basis of cooperation could effectively benefit from a hyperscanning approach. Interbrain connectivity was, in fact, more informative in the investigation of cooperative behavior with respect to established EEG signal processing methodologies applied at a single subject level.

  6. Investigating Cooperative Behavior in Ecological Settings: An EEG Hyperscanning Study.

    Directory of Open Access Journals (Sweden)

    Jlenia Toppi

    Full Text Available The coordinated interactions between individuals are fundamental for the success of the activities in some professional categories. We reported on brain-to-brain cooperative interactions between civil pilots during a simulated flight. We demonstrated for the first time how the combination of neuroelectrical hyperscanning and intersubject connectivity could provide indicators sensitive to the humans' degree of synchronization under a highly demanding task performed in an ecological environment. Our results showed how intersubject connectivity was able to i characterize the degree of cooperation between pilots in different phases of the flight, and ii to highlight the role of specific brain macro areas in cooperative behavior. During the most cooperative flight phases pilots showed, in fact, dense patterns of interbrain connectivity, mainly linking frontal and parietal brain areas. On the contrary, the amount of interbrain connections went close to zero in the non-cooperative phase. The reliability of the interbrain connectivity patterns was verified by means of a baseline condition represented by formal couples, i.e. pilots paired offline for the connectivity analysis but not simultaneously recorded during the flight. Interbrain density was, in fact, significantly higher in real couples with respect to formal couples in the cooperative flight phases. All the achieved results demonstrated how the description of brain networks at the basis of cooperation could effectively benefit from a hyperscanning approach. Interbrain connectivity was, in fact, more informative in the investigation of cooperative behavior with respect to established EEG signal processing methodologies applied at a single subject level.

  7. Cooperation and depressive symptoms.

    Science.gov (United States)

    Brendan Clark, C; Thorne, Christopher B; Hardy, Sonya; Cropsey, Karen L

    2013-09-25

    Deficits in pro-social cooperation are common in many individuals with mental illnesses such as depression. For decades, researchers have used economic game paradigms to compare cross-cultural cooperative behavior. However, research using economic games to assess cooperative behavior in clinical populations is in the early stages. We hypothesized that individuals with greater depressive symptoms would struggle to maintain reciprocity in iterative games, but not in single-iteration games measuring personal values. Participants (n=41) played four computer-based economic games (prisoner's dilemma, the public goods game, the ultimatum game, and the trust game) measuring different aspects of cooperation. Participants completed the Depression Anxiety and Stress Scale (DASS) and other measures of personality and demographics. Analyses assessed the relationships between game performance and psychological distress as measured by the DASS. Significant correlations were found between game performance and depressive symptoms, but not symptoms of anxiety or stress. Performance in the prisoner's dilemma and public goods game was significantly related to depression in a linear regression even when known associations with depressive affect such as age, gender, race, education, marital status, and neuroticism were controlled for. Depressive symptoms were associated with an inability to sustain reciprocal cooperation. Participants showed the predicted deficits in cooperation in these economic games. Economic games show the potential for assessing the social deficits associated with depressive symptoms. © 2013 Elsevier B.V. All rights reserved.

  8. Auction-based Security Game for Multiuser Cooperative Networks

    Science.gov (United States)

    Wang, An; Cai, Yueming; Yang, Wendong; Cheng, Yunpeng

    2013-04-01

    In this paper, we develop an auction-based algorithm to allocate the relay power efficiently to improve the system secrecy rate in a cooperative network, where several source-destination pairs and one cooperative relay are involved. On the one hand, the cooperative relay assists these pairs to transmit under a peak power constraint. On the other hand, the relay is untrusty and is also a passive eavesdropper. The whole auction process is completely distributed and no instantaneous channel state information exchange is needed. We also prove the existence and uniqueness of the Nash Equilibrium (NE) for the proposed power auction game. Moreover, the Pareto optimality is also validated. Simulation results show that our proposed auction-based algorithm can effectively improve the system secrecy rate. Besides, the proposed auction-based algorithm can converge to the unique NE point within a finite number of iterations. More interestingly, we also find that the proposed power auction mechanism is cheat-proof.

  9. Photogeneration of polaron pairs in conducting polymers

    Science.gov (United States)

    Conwell, E. M.; Mizes, H. A.

    1995-03-01

    It is usually assumed that when photogeneration in a conducting polymer results in an electron and hole on separate chains they form negative and positive polarons that can move independently of each other. We show, on the basis of the small carrier yield per photon seen in picosecond photoconductivity, the different behavior of photoinduced absorption (PA) in dilute solution and thin films, and the spectral distribution of the PA in thin films, that photogenerated positive and negative polarons in poly(p-phenylene vinylene), polythiophene, and polyacetylene are, for the most part, bound in pairs by their Coulomb attraction. We also show that PA data give evidence for a gap of 2.8 eV, and thus an exciton binding energy of 0.4 eV, in poly(p-phenylene vinylene).

  10. Vacuum Outer-Gap Structure in Pulsar Outer Magnetospheres

    Institute of Scientific and Technical Information of China (English)

    LIN Gui-Fang; ZHANG Li

    2009-01-01

    We study the vacuum outer-gap structure in the outer magnetosphere of rotation-powered pulsars by considering the limit of trans-field height through a pair production process. In this case, the trans-field height is limited by the photon-photon pair production process and the outer boundary of the outer gap can be extended outside the light cylinder. By solving self-consistently the Poisson equation for electrical potential and the Boltzmann equations of electrons/positrons and γ-rays in a vacuum outer gap for the parameters of Vela pulsar, we obtain an approximate geometry of the outer gap, i.e. the trans-field height is limited by the pair-production process and increases with the radial distance to the star and the width of the outer gap starts at the inner boundary (near the null charge surface) and ends at the outer boundary which locates inside or outside the light cylinder depending on the inclination angle.

  11. Fostering Cooperative Activism through Critical Design

    DEFF Research Database (Denmark)

    Menendez Blanco, Maria; Bjorn, Pernille; De Angeli, Antonella

    2017-01-01

    Critical design is gaining momentum in interaction design, yet little CSCW research has focused on articulating the cooperative potentials of critical design artefacts. We address this gap by reflecting upon a design project aimed at overturning the prevailing narrative regarding dyslexia in Italy....... The adversarial propositions embedded in our critical design artefacts challenged the description of dyslexia as a learning disorder putting forward the view of a learning difference. These artefacts demonstrated their capacity to bridge heterogeneous social worlds (those of teachers, children, and parents...

  12. Estimating Gender Wage Gaps

    Science.gov (United States)

    McDonald, Judith A.; Thornton, Robert J.

    2011-01-01

    Course research projects that use easy-to-access real-world data and that generate findings with which undergraduate students can readily identify are hard to find. The authors describe a project that requires students to estimate the current female-male earnings gap for new college graduates. The project also enables students to see to what…

  13. Closing the Gap

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    China's recent economic success has brought positive changes to its urban population,but left those in the countryside way behind.The gap in income and living standrs that always existed between urban and rural dwellers has widened alarmingly in the past two decades,causing serious problems.

  14. Structuring the Information Gap.

    Science.gov (United States)

    Edge, Julian

    1984-01-01

    Describes an information gap procedure to teach a new structure which requires students to look for and exchange information in order to complete a task in an English as a second language class. Illustrates the method with a set of materials and suggests ways for teachers to produce similar materials. (SED)

  15. 'Mind the Gap!'

    DEFF Research Database (Denmark)

    Persson, Karl Gunnar

    This paper challenges the widely held view that sharply falling real transport costs closed the transatlantic gap in grain prices in the second half of the 19th century. Several new results emerge from an analysis of a new data set of weekly wheat prices and freight costs from New York to UK mark...

  16. Bridging the Technological Gap.

    Science.gov (United States)

    Lazow, Robert; And Others

    The aim of "Bridging the Technological Gap" (BTG), a federally funded demonstration project, is to use microcomputer technology in the rehabilitation of the psychiatrically disabled. Through the use of a custom designed microcomputer software package, clients receive remediation in areas of specific cognitive and behavioral deficits. The project…

  17. Does cooperation mean kinship between spatially discrete ant nests?

    Science.gov (United States)

    Procter, Duncan S; Cottrell, Joan E; Watts, Kevin; A'Hara, Stuart W; Hofreiter, Michael; Robinson, Elva J H

    2016-12-01

    Eusociality is one of the most complex forms of social organization, characterized by cooperative and reproductive units termed colonies. Altruistic behavior of workers within colonies is explained by inclusive fitness, with indirect fitness benefits accrued by helping kin. Members of a social insect colony are expected to be more closely related to one another than they are to other conspecifics. In many social insects, the colony can extend to multiple socially connected but spatially separate nests (polydomy). Social connections, such as trails between nests, promote cooperation and resource exchange, and we predict that workers from socially connected nests will have higher internest relatedness than those from socially unconnected, and noncooperating, nests. We measure social connections, resource exchange, and internest genetic relatedness in the polydomous wood ant Formica lugubris to test whether (1) socially connected but spatially separate nests cooperate, and (2) high internest relatedness is the underlying driver of this cooperation. Our results show that socially connected nests exhibit movement of workers and resources, which suggests they do cooperate, whereas unconnected nests do not. However, we find no difference in internest genetic relatedness between socially connected and unconnected nest pairs, both show high kinship. Our results suggest that neighboring pairs of connected nests show a social and cooperative distinction, but no genetic distinction. We hypothesize that the loss of a social connection may initiate ecological divergence within colonies. Genetic divergence between neighboring nests may build up only later, as a consequence rather than a cause of colony separation.

  18. Evidence for two superconducting gaps in MgB2.

    Science.gov (United States)

    Chen, X K; Konstantinovic, M J; Irwin, J C; Lawrie, D D; Franck, J P

    2001-10-01

    We have measured the Raman spectra of polycrystalline MgB2 from 25 to 1200 cm(-1). A superconductivity-induced redistribution in the electronic Raman continuum was observed. Two pair-breaking peaks appear in the spectra, suggesting the presence of two superconducting gaps. The measured spectra were analyzed using a quasi-two-dimensional model in which two s-wave superconducting gaps open on two sheets of Fermi surface. For the gap values we have obtained Delta(1) = 22 cm(-1) ( 2.7 meV) and Delta(2) = 50 cm(-1) ( 6.2 meV). Our results suggest that a conventional phonon-mediated pairing mechanism occurs in the planar boron sigma bands and is responsible for the superconductivity of MgB2.

  19. PERIODIC COMPLEMENTARY BINARY SEQUENCE PAIRS

    Institute of Scientific and Technical Information of China (English)

    XuChengqian; ZhaoXiaoqun

    2002-01-01

    A new set of binary sequences-Periodic Complementary Binary Sequence Pair (PCSP)is proposed .A new class of block design-Difference Family Pair (DFP)is also proposed .The relationship between PCSP and DFP,the properties and exising conditions of PCSP and the recursive constructions for PCSP are given.

  20. PERIODIC COMPLEMENTARY BINARY SEQUENCE PAIRS

    Institute of Scientific and Technical Information of China (English)

    Xu Chengqian; Zhao Xiaoqun

    2002-01-01

    A new set of binary sequences-Periodic Complementary Binary Sequence Pair (PCSP) is proposed. A new class of block design-Difference Family Pair (DFP) is also proposed.The relationship between PCSP and DFP, the properties and existing conditions of PCSP and the recursive constructions for PCSP are given.

  1. Assessment Strategies for Pair Programming

    Science.gov (United States)

    Hahn, Jan Hendrik; Mentz, Elsa; Meyer, Lukas

    2009-01-01

    Although pair programming has proved its usefulness in teaching and learning programming skills, it is difficult to assess the individual roles and abilities of students whilst programming in pairs. (Note that within this manuscript, the term assessment refers to evaluating individual student performance.) Assessing only the outcomes of a pair…

  2. Instability of vortex pair leapfrogging

    DEFF Research Database (Denmark)

    Tophøj, Laust; Aref, Hassan

    2013-01-01

    pairs fly off to infinity, and a "walkabout" mode, where the vortices depart from leapfrogging but still remain within a finite distance of one another. We show numerically that this transition is more gradual, a result that we relate to earlier investigations of chaotic scattering of vortex pairs [L...

  3. Kramers Pairs in configuration interaction

    DEFF Research Database (Denmark)

    Avery, John Scales; Avery, James Emil

    2003-01-01

    The theory of symmetry-preserving Kramers pair creation operators is reviewed and formulas for applying these operators to configuration interaction calculations are derived. A new and more general type of symmetry-preserving pair creation operator is proposed and shown to commute with the total...

  4. Design of Air Gap for Reducing Torque Ripple in a Single-Phase BLDC Motor

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Byoung Yull; Kwon, Byung II [Hanyang University, Seoul(Korea); Park, Seung Chan [Dong-Yang University,Yeongju(Korea)

    2002-02-01

    Most single-phase brushless DC (BLDC) motors have unequal air gap to eliminate the dead-point where the developed torque value is zero. However this partial increase of the air gap deteriorates the motor characteristics in cogging torque. thus in this paper a new topology of unequal air gap is proposed to solve this problem. The topology is ti use some pairs of equal or unequal air gaps. As a result, it is proved by the finite element analysis and experimental results that the single-phase BLDC motor with the proposed air gap topology is very effective in reducing the cogging torque. (author). 8 refs., 8 figs., 1 tab.

  5. Fundamental Limits of Cooperation

    CERN Document Server

    Lozano, Angel; Andrews, Jeffrey G

    2012-01-01

    Cooperation is viewed as a key ingredient for interference management in wireless systems. This paper shows that cooperation has fundamental limitations. The main result is that even full cooperation between transmitters cannot in general change an interference-limited network to a noise-limited network. The key idea is that there exists a spectral efficiency upper bound that is independent of the transmit power. First, a spectral efficiency upper bound is established for systems that rely on pilot-assisted channel estimation; in this framework, cooperation is shown to be possible only within clusters of limited size, which are subject to out-of-cluster interference whose power scales with that of the in-cluster signals. Second, an upper bound is also shown to exist when cooperation is through noncoherent communication; thus, the spectral efficiency limitation is not a by-product of the reliance on pilot-assisted channel estimation. Consequently, existing literature that routinely assumes the high-power spect...

  6. Pairing mechanism of heavily electron doped FeSe systems: dynamical tuning of the pairing cutoff energy

    Science.gov (United States)

    Bang, Yunkyu

    2016-11-01

    We studied the pairing mechanism of the heavily electron doped FeSe (HEDIS) systems, which commonly have one incipient hole band—a band top below the Fermi level by a finite energy distance ε b —at Γ point and ordinary electron bands at M points in Brillouin zone (BZ). We found that the system allows two degenerate superconducting solutions with the exactly same T c in clean limit: the incipient {s}{he}+/- -gap ({{{Δ }}}h-\

  7. Short versus long term benefits and the evolution of cooperation in the prisoner's dilemma game.

    Directory of Open Access Journals (Sweden)

    Markus Brede

    Full Text Available In this paper I investigate the evolution of cooperation in the prisoner's dilemma when individuals change their strategies subject to performance evaluation of their neighbours over variable time horizons. In the monochrome setting, in which all agents per default share the same performance evaluation rule, weighing past events strongly dramatically enhances the prevalence of cooperators. For co-evolutionary models, in which evaluation time horizons and strategies can co-evolve, I demonstrate that cooperation naturally associates with long-term evaluation of others while defection is typically paired with very short time horizons. Moreover, considering the continuous spectrum in between enhanced and discounted weights of past performance, cooperation is optimally supported when cooperators neither give enhanced weight to past nor more recent events, but simply average payoffs. Payoff averaging is also found to emerge as the dominant strategy for cooperators in co-evolutionary models, thus proposing a natural route to the evolution of cooperation in viscous populations.

  8. Short versus long term benefits and the evolution of cooperation in the prisoner's dilemma game.

    Science.gov (United States)

    Brede, Markus

    2013-01-01

    In this paper I investigate the evolution of cooperation in the prisoner's dilemma when individuals change their strategies subject to performance evaluation of their neighbours over variable time horizons. In the monochrome setting, in which all agents per default share the same performance evaluation rule, weighing past events strongly dramatically enhances the prevalence of cooperators. For co-evolutionary models, in which evaluation time horizons and strategies can co-evolve, I demonstrate that cooperation naturally associates with long-term evaluation of others while defection is typically paired with very short time horizons. Moreover, considering the continuous spectrum in between enhanced and discounted weights of past performance, cooperation is optimally supported when cooperators neither give enhanced weight to past nor more recent events, but simply average payoffs. Payoff averaging is also found to emerge as the dominant strategy for cooperators in co-evolutionary models, thus proposing a natural route to the evolution of cooperation in viscous populations.

  9. Reduction of Gap Junctional Conductance by Microinjection of Antibodies against the 27-kDa Liver Gap Junction Polypeptide

    Science.gov (United States)

    Hertzberg, E. L.; Spray, D. C.; Bennett, M. V. L.

    1985-04-01

    Antibody raised against isolated rat liver gap junctions was microinjected into coupled cells in culture to assess its influence on gap junctional conductance. A rapid inhibition of fluorescent dye transfer and electrical coupling was produced in pairs of freshly dissociated adult rat hepatocytes and myocardial cells as well as in pairs of superior cervical ganglion neurons from neonatal rats cultured under conditions in which electrotonic synapses form. The antibodies have been shown by indirect immunofluorescence to bind to punctate regions of the plasma membrane in liver. By immunoreplica analysis of rat liver homogenates, plasma membranes, and isolated gap junctions resolved on NaDodSO4/polyacrylamide gels, binding was shown to be specific for the 27-kDa major polypeptide of gap junctions. This and similar antibodies should provide a tool for further investigation of the role of cell-cell communication mediated by gap junctions and indicate that immunologically similar polypeptides comprise gap junctions in adult mammalian cells derived from all three germ layers.

  10. Minding the Gap

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Millicent Anne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-23

    Neutron & X-ray scattering provides nano- to meso-scale details of complex fluid structure; 1D electronic density maps dervied from SAXS yield molecular level insights; Neutron reflectivity provides substructure details of substrate supported complex fluids; Complex fluids composition can be optimized to support a wide variety of both soluble and membrane proteins; The water gap dimensions can be finely tuned through polymer component.

  11. Small Generation Gap

    Institute of Scientific and Technical Information of China (English)

    JANE SHAW

    1994-01-01

    IT was while I was making milk for my son that I discovered the generation gap between us. A little thing of two years and three months, my son stood on a big chair I brought him and joined me to make milk. Holding a small spoon in his plump little hand, he scooped flour out of a jar and poured it into the feeding bottle and then scooped milk powder and

  12. Pair density wave superconducting states and statistical mechanics of dimers

    Science.gov (United States)

    Soto Garrido, Rodrigo Andres

    The following thesis is divided in two main parts. Chapters 2, 3 and 4 are devoted to the study of the so called pair-density-wave (PDW) superconducting state and some of its connections to electronic liquid crystal (ELC) phases, its topological aspects in a one dimensional model and its appearance in a quasi-one dimensional system. On the other hand, chapter 5 is focused on the investigation of the classical statistical mechanics properties of dimers, in particular, the dimer model on the Aztec diamond graph and its relation with the octahedron equation. In chapter 2 we present a theory of superconducting states where the Cooper pairs have a nonzero center-of-mass momentum, inhomogeneous superconducting states known as a pair-density-waves (PDWs) states. We show that in a system of spin-1/2 fermions in two dimensions in an electronic nematic spin-triplet phase where rotational symmetry is broken in both real and spin space PDW phases arise naturally in a theory that can be analysed using controlled approximations. We show that several superfluid phases that may arise in this phase can be treated within a controlled BCS mean field theory, with the strength of the spin-triplet nematic order parameter playing the role of the small parameter of this theory. We find that in a spin-triplet nematic phase, in addition to a triplet p-wave and spin-singlet d-wave (or s depending on the nematic phase) uniform superconducting states, it is also possible to have a d-wave (or s) PDW superconductor. The PDW phases found here can be either unidirectional, bidirectional, or tridirectional depending on the spin-triplet nematic phase and which superconducting channel is dominant. In addition, a triple-helix state is found in a particular channel. We show that these PDW phases are present in the weak-coupling limit, in contrast to the usual Fulde-Ferrell-Larkin-Ovchinnikov phases, which require strong coupling physics in addition to a large magnetic field (and often both). In chapter

  13. Evolution, epigenetics and cooperation

    Indian Academy of Sciences (India)

    Patrick Bateson

    2014-04-01

    Explanations for biological evolution in terms of changes in gene frequencies refer to outcomes rather than process. Integrating epigenetic studies with older evolutionary theories has drawn attention to the ways in which evolution occurs. Adaptation at the level of the gene is givingway to adaptation at the level of the organism and higher-order assemblages of organisms. These ideas impact on the theories of how cooperation might have evolved. Two of the theories, i.e. that cooperating individuals are genetically related or that they cooperate for self-interested reasons, have been accepted for a long time. The idea that adaptation takes place at the level of groups is much more controversial. However, bringing together studies of development with those of evolution is taking away much of the heat in the debate about the evolution of group behaviour.

  14. Cooperative Prototyping Experiments

    DEFF Research Database (Denmark)

    Bødker, Susanne; Grønbæk, Kaj

    1989-01-01

    This paper describes experiments with a design technique that we denote cooperative prototyping. The experiments consider design of a patient case record system for municipal dental clinics in which we used HyperCard, an off the shelf programming environment for the Macintosh. In the ecperiments we...... tried to achieve a fluent work-like evaluation of prototypes where users envisioned future work with a computer tool, at the same time as we made on-line modifications of prototypes in cooperation with the users when breakdown occur in their work-like evaluation. The experiments showed...... these experiences we discuss problems in the process, requirements for design tools, and issues involved in getting going with cooperative prototyping with active user involvement....

  15. Evolution, epigenetics and cooperation.

    Science.gov (United States)

    Bateson, Patrick

    2014-04-01

    Explanations for biological evolution in terms of changes in gene frequencies refer to outcomes rather than process. Integrating epigenetic studies with older evolutionary theories has drawn attention to the ways in which evolution occurs. Adaptation at the level of the gene is givingway to adaptation at the level of the organism and higher-order assemblages of organisms. These ideas impact on the theories of how cooperation might have evolved. Two of the theories, i.e. that cooperating individuals are genetically related or that they cooperate for self-interested reasons, have been accepted for a long time. The idea that adaptation takes place at the level of groups is much more controversial. However, bringing together studies of development with those of evolution is taking away much of the heat in the debate about the evolution of group behaviour.

  16. Cooperative Prototyping Experiments

    DEFF Research Database (Denmark)

    Bødker, Susanne; Grønbæk, Kaj

    1989-01-01

    This paper describes experiments with a design technique that we denote cooperative prototyping. The experiments consider design of a patient case record system for municipal dental clinics in which we used HyperCard, an off the shelf programming environment for the Macintosh. In the ecperiments we...... tried to achieve a fluent work-like evaluation of prototypes where users envisioned future work with a computer tool, at the same time as we made on-line modifications of prototypes in cooperation with the users when breakdown occur in their work-like evaluation. The experiments showed...... that it was possible to make a number of direct manipulation changes of prototypes in cooperation with the users, in interplay with their fluent work-like evaluation of these. However, breakdown occurred in the prototyping process when we reached the limits of the direct manipulation support for modification. From...

  17. A transcript finishing initiative for closing gaps in the human transcriptome

    DEFF Research Database (Denmark)

    Sogayar, Mari Cleide; Camargo, Anamaria A; Bettoni, Fabiana

    2004-01-01

    We report the results of a transcript finishing initiative, undertaken for the purpose of identifying and characterizing novel human transcripts, in which RT-PCR was used to bridge gaps between paired EST clusters, mapped against the genomic sequence. Each pair of EST clusters selected for experi...

  18. Threshold Games and Cooperation on Multiplayer Graphs.

    Directory of Open Access Journals (Sweden)

    Kaare B Mikkelsen

    Full Text Available The study investigates the effect on cooperation in multiplayer games, when the population from which all individuals are drawn is structured-i.e. when a given individual is only competing with a small subset of the entire population.To optimize the focus on multiplayer effects, a class of games were chosen for which the payoff depends nonlinearly on the number of cooperators-this ensures that the game cannot be represented as a sum of pair-wise interactions, and increases the likelihood of observing behaviour different from that seen in two-player games. The chosen class of games are named "threshold games", and are defined by a threshold, M > 0, which describes the minimal number of cooperators in a given match required for all the participants to receive a benefit. The model was studied primarily through numerical simulations of large populations of individuals, each with interaction neighbourhoods described by various classes of networks.When comparing the level of cooperation in a structured population to the mean-field model, we find that most types of structure lead to a decrease in cooperation. This is both interesting and novel, simply due to the generality and breadth of relevance of the model-it is likely that any model with similar payoff structure exhibits related behaviour. More importantly, we find that the details of the behaviour depends to a large extent on the size of the immediate neighbourhoods of the individuals, as dictated by the network structure. In effect, the players behave as if they are part of a much smaller, fully mixed, population, which we suggest an expression for.

  19. Pairing Correlations at High Spins

    Science.gov (United States)

    Ma, Hai-Liang; Dong, Bao-Guo; Zhang, Yan; Fan, Ping; Yuan, Da-Qing; Zhu, Shen-Yun; Zhang, Huan-Qiao; Petrache, C. M.; Ragnarsson, I.; Carlsson, B. G.

    The pairing correcting energies at high spins in 161Lu and 138Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.

  20. GapBlaster-A Graphical Gap Filler for Prokaryote Genomes.

    Science.gov (United States)

    de Sá, Pablo H C G; Miranda, Fábio; Veras, Adonney; de Melo, Diego Magalhães; Soares, Siomar; Pinheiro, Kenny; Guimarães, Luis; Azevedo, Vasco; Silva, Artur; Ramos, Rommel T J

    2016-01-01

    The advent of NGS (Next Generation Sequencing) technologies has resulted in an exponential increase in the number of complete genomes available in biological databases. This advance has allowed the development of several computational tools enabling analyses of large amounts of data in each of the various steps, from processing and quality filtering to gap filling and manual curation. The tools developed for gap closure are very useful as they result in more complete genomes, which will influence downstream analyses of genomic plasticity and comparative genomics. However, the gap filling step remains a challenge for genome assembly, often requiring manual intervention. Here, we present GapBlaster, a graphical application to evaluate and close gaps. GapBlaster was developed via Java programming language. The software uses contigs obtained in the assembly of the genome to perform an alignment against a draft of the genome/scaffold, using BLAST or Mummer to close gaps. Then, all identified alignments of contigs that extend through the gaps in the draft sequence are presented to the user for further evaluation via the GapBlaster graphical interface. GapBlaster presents significant results compared to other similar software and has the advantage of offering a graphical interface for manual curation of the gaps. GapBlaster program, the user guide and the test datasets are freely available at https://sourceforge.net/projects/gapblaster2015/. It requires Sun JDK 8 and Blast or Mummer.

  1. GapBlaster-A Graphical Gap Filler for Prokaryote Genomes.

    Directory of Open Access Journals (Sweden)

    Pablo H C G de Sá

    Full Text Available The advent of NGS (Next Generation Sequencing technologies has resulted in an exponential increase in the number of complete genomes available in biological databases. This advance has allowed the development of several computational tools enabling analyses of large amounts of data in each of the various steps, from processing and quality filtering to gap filling and manual curation. The tools developed for gap closure are very useful as they result in more complete genomes, which will influence downstream analyses of genomic plasticity and comparative genomics. However, the gap filling step remains a challenge for genome assembly, often requiring manual intervention. Here, we present GapBlaster, a graphical application to evaluate and close gaps. GapBlaster was developed via Java programming language. The software uses contigs obtained in the assembly of the genome to perform an alignment against a draft of the genome/scaffold, using BLAST or Mummer to close gaps. Then, all identified alignments of contigs that extend through the gaps in the draft sequence are presented to the user for further evaluation via the GapBlaster graphical interface. GapBlaster presents significant results compared to other similar software and has the advantage of offering a graphical interface for manual curation of the gaps. GapBlaster program, the user guide and the test datasets are freely available at https://sourceforge.net/projects/gapblaster2015/. It requires Sun JDK 8 and Blast or Mummer.

  2. Conventional and Unconventional Pairing and Condensates in Dilute Nuclear Matter

    CERN Document Server

    Clark, John W; Stein, Martin; Huang, Xu-Guang; Khodel, Victor A; Shaginyan, Vasily R; Zverev, Mikhail V

    2016-01-01

    This contribution will survey recent progress toward an understanding of diverse pairing phenomena in dilute nuclear matter at small and moderate isospin asymmetry, with results of potential relevance to supernova envelopes and proto-neutron stars. Application of {\\it ab initio} many-body techniques has revealed a rich array of temperature-density phase diagrams, indexed by isospin asymmetry, which feature both conventional and unconventional superfluid phases. At low density there exist a homogeneous translationally invariant BCS phase, a homogeneous LOFF phase violating translational invariance, and an inhomogeneous translationally invariant phase-separated BCS phase. The transition from the BCS to the BEC phases is characterized in terms of the evolution, from weak to strong coupling, of the pairing gap, condensate wave function, and quasiparticle occupation numbers and spectra. Additionally, a schematic formal analysis of pairing in neutron matter at low to moderate densities is presented that establishes...

  3. Introduction: cooperative learning

    Directory of Open Access Journals (Sweden)

    José-Manuel Serrano

    2014-10-01

    Full Text Available The principal objective of this revision is the recognition of cooperative learning as a highly effective strategy for the accomplishment of the general goals in learning. The different investigations assessed validate the potential that a cooperative organization of the classroom could entail for academic achievement, self-esteem, interpersonal attraction or social support. The solidity of the existing research contributes to its external and internal validity and, thus, to conclude that the results are consistent and can be extrapolated to different cultures, ethnic groups or countries.

  4. Cooperative internal conversion process

    CERN Document Server

    Kálmán, Péter

    2015-01-01

    A new phenomenon, called cooperative internal conversion process, in which the coupling of bound-free electron and neutron transitions due to the dipole term of their Coulomb interaction permits cooperation of two nuclei leading to neutron exchange if it is allowed by energy conservation, is discussed theoretically. General expression of the cross section of the process is reported in one particle nuclear and spherical shell models as well in the case of free atoms (e.g. noble gases). A half-life characteristic of the process is also determined. The case of $Ne$ is investigated numerically. The process may have significance in fields of nuclear waste disposal and nuclear energy production.

  5. Nordic Energy Policy Cooperation

    DEFF Research Database (Denmark)

    Jørgensen, Birte Holst

    2016-01-01

    the borders long before the politicians supported and pushed for further cooperation. Energy efficiency was addressed by a portfolio of activities ranging from knowledge-sharing, public campaigns, labelling and standardisation of products. The need to address environmental degradation was inspired by the UN...... officials. With the consolidation of Nordic Energy Research in 1999, the cooperation benefitted from having an institution that exclusively could focus on Nordic energy policy issues and deliver research-based decision support to decision makers in the Nordic energy sector....

  6. Cooperative strategies in innovation

    Directory of Open Access Journals (Sweden)

    Ratner Svetlana Valerevna

    2013-12-01

    Full Text Available In the knowledge economy one of the conventional ways to obtain economic agents access to new knowledge and technology is the creation and implementation of specific cooperative strategies, such as the formation of alliances with other economic agents. Combining competencies partners in joint research and development has a positive impact on innovation, but it is a partial convergence of competences partners that in the long term can lead to the unification of competences agents economic system and reduce their innovative activity. In this paper, we propose an effective method of information management in the implementation of a cooperative strategy of innovation.

  7. Proto-cooperation

    DEFF Research Database (Denmark)

    Herbert-Read, James E; Romanczuk, Pawel; Krause, Stefan;

    2016-01-01

    beneficial if the cost of attacking is high, and only then when waiting times are short. Our findings provide evidence that cooperative benefits can be realized through the facilitative effects of individuals' hunting actions without spatial coordination of attacks. Such 'proto-cooperation' may be the pre...... in an increase of injured fish in the school with the number of attacks. How quickly prey are captured is positively correlated with the level of injury of the school, suggesting that hunters can benefit from other conspecifics' attacks on the prey. To explore this, we built a mathematical model capturing...

  8. Cooperatives between truth and validity

    Directory of Open Access Journals (Sweden)

    Guilherme Krueger

    2014-12-01

    Full Text Available The current declaration of the International Cooperative Alliance on cooperative identity since its 1995 Centennial Conference (which was held in Manchester makes no distinction between cooperation and cooperative. The lack of distinction between cooperation and cooperative has caused the Decennial Cooperative Action Plan to define cooperatives as a form, while their materiality is regarded as managerial: a business (activity under a cooperative form. An identity that is close to us cannot be reduced to form, without this being a problem. Therefore, the value underlying this identity —cooperation— must have a substantial basis, even if it is idealised, if it is to affect us.Received: 27.03.2014Accepted: 12.05.2014

  9. Social penalty promotes cooperation in a cooperative society.

    Science.gov (United States)

    Ito, Hiromu; Yoshimura, Jin

    2015-08-04

    Why cooperation is well developed in human society is an unsolved question in biological and human sciences. Vast studies in game theory have revealed that in non-cooperative games selfish behavior generally dominates over cooperation and cooperation can be evolved only under very limited conditions. These studies ask the origin of cooperation; whether cooperation can evolve in a group of selfish individuals. In this paper, instead of asking the origin of cooperation, we consider the enhancement of cooperation in a small already cooperative society. We ask whether cooperative behavior is further promoted in a small cooperative society in which social penalty is devised. We analyze hawk-dove game and prisoner's dilemma introducing social penalty. We then expand it for non-cooperative games in general. The results indicate that cooperation is universally favored if penalty is further imposed. We discuss the current result in terms of the moral, laws, rules and regulations in a society, e.g., criminology and traffic violation.

  10. Stereochemical plasticity modulates cooperative binding in a CoII12L6 cuboctahedron

    Science.gov (United States)

    Rizzuto, Felix J.; Nitschke, Jonathan R.

    2017-09-01

    Biomolecular receptors are able to process information by responding differentially to combinations of chemical signals. Synthetic receptors that are likewise capable of multi-stimuli response can form the basis of programmable molecular systems, wherein specific input sequences create distinct outputs. Here we report a pseudo-cuboctahedral assembly capable of cooperatively binding anionic and neutral guest species. The binding of pairs of fullerene guests was observed to effect the all-or-nothing cooperative templation of an S6-symmetric host stereoisomer. This bis-fullerene adduct exhibits different cooperativity in binding pairs of anions from the fullerene-free parent: in one case, positive cooperativity is observed, while in another all binding affinities are enhanced by an order of magnitude, and in a third the binding events are only minimally perturbed. This intricate modulation of binding affinity, and thus cooperativity, renders our new cuboctahedral receptor attractive for incorporation into systems with complex, programmable responses to different sets of stimuli.

  11. Exact solution for generalized pairing

    OpenAIRE

    Pan, Feng; J.P. Draayer

    1997-01-01

    An infinite dimensional algebra, which is useful for deriving exact solutions of the generalized pairing problem, is introduced. A formalism for diagonalizing the corresponding Hamiltonian is also proposed. The theory is illustrated with some numerical examples.

  12. Pairing mechanisms for binary stars

    CERN Document Server

    Kouwenhoven, M B N; Goodwin, S P; Zwart, S F Portegies; Kaper, L; 10.1002/asna.200811061

    2008-01-01

    Knowledge of the binary population in stellar groupings provides important information about the outcome of the star forming process in different environments. Binarity is also a key ingredient in stellar population studies and is a prerequisite to calibrate the binary evolution channels. In these proceedings we present an overview of several commonly used methods to pair individual stars into binary systems, which we refer to as the pairing function. Many pairing functions are frequently used by observers and computational astronomers, either for the mathematical convenience, or because they roughly describe the expected outcome of the star forming process. We discuss the consequences of each pairing function for the interpretation of observations and numerical simulations. The binary fraction and mass ratio distribution generally depend strongly on the selection of the range in primary spectral type in a sample. These quantities, when derived from a binary survey with a mass-limited sample of target stars, ...

  13. Optimal Grouping and Matching for Network-Coded Cooperative Communications

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, S; Shi, Y; Hou, Y T; Kompella, S; Midkiff, S F

    2011-11-01

    Network-coded cooperative communications (NC-CC) is a new advance in wireless networking that exploits network coding (NC) to improve the performance of cooperative communications (CC). However, there remains very limited understanding of this new hybrid technology, particularly at the link layer and above. This paper fills in this gap by studying a network optimization problem that requires joint optimization of session grouping, relay node grouping, and matching of session/relay groups. After showing that this problem is NP-hard, we present a polynomial time heuristic algorithm to this problem. Using simulation results, we show that our algorithm is highly competitive and can produce near-optimal results.

  14. Atomic pair-state interferometer

    DEFF Research Database (Denmark)

    Nipper, J.; Balewski, Jonathan B.; Krupp, Alexander T.

    2012-01-01

    to measure the phase shift. Although the coupling between pair states is coherent on the time scale of the experiment, a loss of visibility occurs as a pair-state interferometer involves three simultaneously interfering paths and only one of them is phase shifted by the mutual interaction. Despite additional...... dephasing mechanisms, a pulsed Förster coupling sequence allows for observation of coherent dynamics around the Förster resonance....

  15. Dual pairs in fluid dynamics

    CERN Document Server

    Gay-Balmaz, François

    2010-01-01

    This paper is a rigorous study of the dual pair structure of the ideal fluid and the dual pair structure for the $n$-dimensional Camassa-Holm (EPDiff) equation, including the proofs of the necessary transitivity results. In the case of the ideal fluid, we show that a careful definition of the momentum maps leads naturally to central extensions of diffeomorphism groups such as the group of quantomorphisms and the Ismagilov central extension.

  16. Counting pairs of faint galaxies

    CERN Document Server

    Woods, D; Richer, H B; Woods, David; Fahlman, Gregory G; Richer, Harvey B

    1995-01-01

    The number of close pairs of galaxies observed to faint magnitude limits, when compared to nearby samples, determines the interaction or merger rate as a function of redshift. The prevalence of mergers at intermediate redshifts is fundamental to understanding how galaxies evolve and the relative population of galaxy types. Mergers have been used to explain the excess of galaxies in faint blue counts above the numbers expected from no-evolution models. Using deep CFHT (I\\leq24) imaging of a ``blank'' field we find a pair fraction which is consistent with the galaxies in our sample being randomly distributed with no significant excess of ``physical'' close pairs. This is contrary to the pair fraction of 34\\%\\pm9\\% found by Burkey {\\it et al.} for similar magnitude limits and using an identical approach to the pair analysis. Various reasons for this discrepancy are discussed. Colors and morphologies of our close pairs are consistent with the bulk of them being random superpositions although, as indicators of int...

  17. Three carbon pairs in Si

    Energy Technology Data Exchange (ETDEWEB)

    Docaj, A. [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States); Estreicher, S.K., E-mail: Stefan.Estreicher@ttu.edu [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States)

    2012-08-01

    Carbon impurities in Si are common in floating-zone and cast-Si materials. The simplest and most discussed carbon complex is the interstitial-substitutional C{sub i}C{sub s} pair, which readily forms when self-interstitials are present in the material. This pair has three possible configurations, each of which is electrically active. The less common C{sub s}C{sub s} pair has been studied in irradiated material but has also recently been seen in as-grown C-rich cast-Si, which is commonly used to fabricate solar cells. The third pair consists of two interstitial C atoms: C{sub i}C{sub i}. Although its formation probability is low for several reasons, the C{sub i}C{sub i} pair is very stable and electrically inactive. In this contribution, we report preliminary results of first-principles calculations of these three C pairs in Si. The structures, binding energies, vibrational spectra, and electrical activity are predicted.

  18. A User Cooperation Stimulating Strategy Based on Cooperative Game Theory in Cooperative Relay Networks

    Directory of Open Access Journals (Sweden)

    Ping Zhang

    2009-01-01

    Full Text Available This paper proposes a user cooperation stimulating strategy among rational users. The strategy is based on cooperative game theory and enacted in the context of cooperative relay networks. Using the pricing-based mechanism, the system is modeled initially with two nodes and a Base Station (BS. Within this framework, each node is treated as a rational decision maker. To this end, each node can decide whether to cooperate and how to cooperate. Cooperative game theory assists in providing an optimal system utility and provides fairness among users. Under different cooperative forwarding modes, certain questions are carefully investigated, including “what is each node's best reaction to maximize its utility?” and “what is the optimal reimbursement to encourage cooperation?” Simulation results show that the nodes benefit from the proposed cooperation stimulating strategy in terms of utility and thus justify the fairness between each user.

  19. Indian Ocean Rim Cooperation

    DEFF Research Database (Denmark)

    Wippel, Steffen

    Since the mid-1990s, the Indian Ocean has been experiencing increasing economic cooperation among its rim states. Middle Eastern countries, too, participate in the work of the Indian Ocean Rim Association, which received new impetus in the course of the current decade. Notably Oman is a very active...

  20. Predicting Human Cooperation.

    Directory of Open Access Journals (Sweden)

    John J Nay

    Full Text Available The Prisoner's Dilemma has been a subject of extensive research due to its importance in understanding the ever-present tension between individual self-interest and social benefit. A strictly dominant strategy in a Prisoner's Dilemma (defection, when played by both players, is mutually harmful. Repetition of the Prisoner's Dilemma can give rise to cooperation as an equilibrium, but defection is as well, and this ambiguity is difficult to resolve. The numerous behavioral experiments investigating the Prisoner's Dilemma highlight that players often cooperate, but the level of cooperation varies significantly with the specifics of the experimental predicament. We present the first computational model of human behavior in repeated Prisoner's Dilemma games that unifies the diversity of experimental observations in a systematic and quantitatively reliable manner. Our model relies on data we integrated from many experiments, comprising 168,386 individual decisions. The model is composed of two pieces: the first predicts the first-period action using solely the structural game parameters, while the second predicts dynamic actions using both game parameters and history of play. Our model is successful not merely at fitting the data, but in predicting behavior at multiple scales in experimental designs not used for calibration, using only information about the game structure. We demonstrate the power of our approach through a simulation analysis revealing how to best promote human cooperation.

  1. Communication, Coordination, Cooperation.

    Science.gov (United States)

    Rose, Nancy Oft; Wiper, Kathie Tippens

    Speech communication teachers at both secondary and postsecondary school levels must cooperate to improve oral communication education. Despite the importance of oral communication skills, speech courses are rarely required in high school. Teachers must tell school boards, higher education boards, and faculties of the importance of speaking and…

  2. Cooperative social capital

    Directory of Open Access Journals (Sweden)

    Oscar Acera Manero

    2005-12-01

    Full Text Available Social capital consists of the contributions of members and associates, both mandatory and voluntary. From an accounting point of view, it is a liability figure that expresses the value of a portion of the equity of the cooperative. Its inclusion in the liability is not the fact that it is a debt but by its nature unenforceable.

  3. Family Sequencing and Cooperation

    NARCIS (Netherlands)

    Grundel, S.; Ciftci, B.B.; Borm, P.E.M.; Hamers, H.J.M.

    2012-01-01

    To analyze the allocation problem of the maximal cost savings of the whole group of jobs, we define and analyze a so-called corresponding cooperative family sequencing game which explicitly takes into account the maximal cost savings for any coalition of jobs. Using nonstandard techniques we prove t

  4. Cooperation Or Conflict?

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Iran’s recent actions have created confusion and heightened doubt about the future of the nuclear issue Recent events involving Iran have produced high drama. First, the country said it would cooperate with the International Atomic Energy Agency (IAEA) on the

  5. Physicality and Cooperative Design

    NARCIS (Netherlands)

    Vyas, Dhaval; Heylen, Dirk K.J.; Nijholt, Antinus; Popescu-Belis, Andrei; Stiefelhagen, Rainer

    2008-01-01

    CSCW researchers have increasingly come to realize that material work setting and its population of artefacts play a crucial part in coordination of distributed or co-located work. This paper uses the notion of physicality as a basis to understand cooperative work. Using examples from an ongoing

  6. Communication, Coordination, Cooperation.

    Science.gov (United States)

    Rose, Nancy Oft; Wiper, Kathie Tippens

    Speech communication teachers at both secondary and postsecondary school levels must cooperate to improve oral communication education. Despite the importance of oral communication skills, speech courses are rarely required in high school. Teachers must tell school boards, higher education boards, and faculties of the importance of speaking and…

  7. Educating for World Cooperation.

    Science.gov (United States)

    Berman, Louise M.; Miel, Alice

    This booklet presents a variety of perspectives on educating for world cooperation. Section 1 discusses major world problems and calls for the reorientation of education as a potential solution. Section 2 deals with the design of such a reorientation and offers three approaches to teaching and curriculum development--knowing, being, and doing. In…

  8. Indian Ocean Rim Cooperation

    DEFF Research Database (Denmark)

    Wippel, Steffen

    Since the mid-1990s, the Indian Ocean has been experiencing increasing economic cooperation among its rim states. Middle Eastern countries, too, participate in the work of the Indian Ocean Rim Association, which received new impetus in the course of the current decade. Notably Oman is a very active...

  9. Cooperation Across the Pacific

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China and Mexico, two significant developing countries in the world, have been strengthening cooperation in all fields in recent years. And the two countries are confident about improving their ties in the future. Mexican Foreign Minister Luis Ernesto Derbez Bautista shares his views on bilateral relations in a written response to questions from Beijing Review reporter Ding Ying.

  10. Cooperation Beats Conflict

    Institute of Scientific and Technical Information of China (English)

    DING YING

    2011-01-01

    Philippine President Benigno Aquino Ⅲ recently completed a five-day visit to China,his first state visit to China since he took office last year.The two countries reached consensus on promoting all-round cooperation,especially in trade and the economy,and downplayed disputes in the South China Sea.

  11. Cooperative Mobile Sensing Networks

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, R S; Kent, C A; Jones, E D; Cunningham, C T; Armstrong, G W

    2003-02-10

    A cooperative control architecture is presented that allows a fleet of Unmanned Air Vehicles (UAVs) to collect data in a parallel, coordinated and optimal manner. The architecture is designed to react to a set of unpredictable events thereby allowing data collection to continue in an optimal manner.

  12. Gap junction channels and cardiac impulse propagation.

    Science.gov (United States)

    Desplantez, Thomas; Dupont, Emmanuel; Severs, Nicholas J; Weingart, Robert

    2007-08-01

    The role of gap junction channels on cardiac impulse propagation is complex. This review focuses on the differential expression of connexins in the heart and the biophysical properties of gap junction channels under normal and disease conditions. Structural determinants of impulse propagation have been gained from biochemical and immunocytochemical studies performed on tissue extracts and intact cardiac tissue. These have defined the distinctive connexin coexpression patterns and relative levels in different cardiac tissues. Functional determinants of impulse propagation have emerged from electrophysiological experiments carried out on cell pairs. The static properties (channel number and conductance) limit the current flow between adjacent cardiomyocytes and thus set the basic conduction velocity. The dynamic properties (voltage-sensitive gating and kinetics of channels) are responsible for a modulation of the conduction velocity during propagated action potentials. The effect is moderate and depends on the type of Cx and channel. For homomeric-homotypic channels, the influence is small to medium; for homomeric-heterotypic channels, it is medium to strong. Since no data are currently available on heteromeric channels, their influence on impulse propagation is speculative. The modulation by gap junction channels is most prominent in tissues at the boundaries between cardiac tissues such as sinoatrial node-atrial muscle, atrioventricular node-His bundle, His bundle-bundle branch and Purkinje fibers-ventricular muscle. The data predict facilitation of orthodromic propagation.

  13. Gap Opening in 3D: Single Planet Gaps

    CERN Document Server

    Fung, Jeffrey

    2016-01-01

    Giant planets can clear deep gaps when embedded in 2D (razor-thin) viscous circumstellar disks. We show by direct simulation that giant planets are just as capable of carving out gaps in 3D. Surface density maps are similar between 2D and 3D, even in detail. In particular, the scaling $\\Sigma_{\\rm gap} \\propto q^{-2}$ of gap surface density with planet mass, derived from a global "zero-dimensional" balance of Lindblad and viscous torques, applies equally well to results obtained at higher dimensions. Our 3D simulations reveal extensive, near-sonic, meridional flows both inside and outside the gaps; these large-scale circulations might bear on disk compositional gradients, in dust or other chemical species. At high planet mass, gap edges are mildly Rayleigh unstable and intermittently shed streams of material into the gap - less so in 3D than in 2D.

  14. [Social cooperatives in Italy].

    Science.gov (United States)

    Villotti, P; Zaniboni, S; Fraccaroli, F

    2014-06-01

    This paper describes the role of social cooperatives in Italy as a type of economic, non-profit organization and their role in contributing to the economic and social growth of the country. The purpose of this paper is to learn more about the experience of the Italian social cooperatives in promoting the work integration process of disadvantaged workers, especially those suffering from mental disorders, from a theoretical and an empirical point of view. Social enterprise is the most popular and consolidated legal and organizational model for social enterprises in Italy, introduced by Law 381/91. Developed during the early 1980s, and formally recognized by law in the early 1990s, social cooperatives aim at pursuing the general interest of the community to promote the human needs and social inclusion of citizens. They are orientated towards aims that go beyond the interest of the business owners, the primary beneficiary of their activities is the community, or groups of disadvantaged people. In Italy, Law 381/91 distinguishes between two categories of social cooperatives, those producing goods of social utility, such as culture, welfare and educational services (A-type), and those providing economic activities for the integration of disadvantaged people into employment (B-type). The main purpose of B-type social cooperatives is to integrate disadvantaged people into the open labour market. This goal is reached after a period of training and working experience inside the firm, during which the staff works to improve both the social and professional abilities of disadvantaged people. During the years, B-type social co-ops acquired a particular relevance in the care of people with mental disorders by offering them with job opportunities. Having a job is central in the recovery process of people suffering from mental diseases, meaning that B-type social co-ops in Italy play an important rehabilitative and integrative role for this vulnerable population of workers. The

  15. Unveiling the Gap

    DEFF Research Database (Denmark)

    Jensson, Pall; Rokkjær, Ole; Nørgaard, Bente

    discussing their NQF and Sweden has decided not to adjust to the EQF for the moment. Analysis of the subject focus for the individual programmes showed a high degree of variation. In the context of CDIO this means that what seems to be a well-known and commonly accepted definition of a discipline like IE...... needs, how universities decide what to teach, and how to bridge the gap. Do the university programs simply reflect the expertise of the faculty members? Is there need for increasing emphasis on continuing education? Is life-long education the answer, and has this been addressed by the CDIO community?...

  16. Mind the gap

    Energy Technology Data Exchange (ETDEWEB)

    Bhagwat, M.S.; Roberts, C.D. [Argonne National Laboratory, Physics Division, Argonne, IL (United States); Krassnigg, A. [Universitaet Graz, Fachbereich Theoretische Physik, Graz (Austria); Maris, P. [University of Pittsburgh, Department of Physics and Astronomy, PA (United States)

    2007-03-15

    In this summary of the application of Dyson-Schwinger equations to the theory and phenomenology of hadrons, some deductions following from a nonperturbative, symmetry-preserving truncation are highlighted, notable amongst which are results for pseudoscalar mesons. We also describe inferences from the gap equation relating to the radius of convergence of a chiral expansion, applications to heavy-light and heavy-heavy mesons, and quantitative estimates of the contribution of quark orbital angular momentum in pseudoscalar mesons; and recapitulate upon studies of nucleon electromagnetic form factors. (orig.)

  17. Mind the gap.

    Energy Technology Data Exchange (ETDEWEB)

    Bhagwat, M. S.; Krassnigg, A.; Maris, P.; Roberts, C. D.; Physics; Univ. Graz; Univ. of Pittsburgh

    2007-03-01

    In this summary of the application of Dyson-Schwinger equations to the theory and phenomenology of hadrons, some deductions following from a nonperturbative, symmetry-preserving truncation are highlighted, notable amongst which are results for pseudoscalar mesons. We also describe inferences from the gap equation relating to the radius of convergence of a chiral expansion, applications to heavy-light and heavy-heavy mesons, and quantitative estimates of the contribution of quark orbital angular momentum in pseudoscalar mesons; and recapitulate upon studies of nucleon electromagnetic form factors.

  18. Photonic band gap materials

    Science.gov (United States)

    Cassagne, D.

    Photonic band gap materials Photonic band gap materials are periodic dielectric structures that control the propagation of electromagnetic waves. We describe the plane wave method, which allows to calculate the band structures of photonic crystals. By symmetry analysis and a perturbative approach, we predict the appearance of the low energy photonic band gaps of hexagonal structures. We propose new two-dimensional structures called graphite and boron nitride. Using a transfer matrix method, we calculate the transmission of the graphite structure and we show the crucial role of the coupling with external modes. We study the appearance of allowed modes in the photonic band gap by the introduction of localized defects in the periodicity. Finally, we discuss the properties of opals formed by self-organized silica microspheres, which are very promising for the fabrication of three-dimensional photonic crystals. Les matériaux à bandes interdites photoniques sont des structures diélectriques périodiques qui contrôlent la propagation des ondes électromagnétiques. Nous décrivons la méthode des ondes planes qui permet de calculer les structures de bandes des cristaux photoniques. Par une analyse de la symétrie et une approche perturbative, nous précisons les conditions d'existence des bandes interdites de basse énergie. Nous proposons de nouvelles structures bidimensionnelles appelées graphite et nitrure de bore. Grâce à une méthode de matrices de transfert, nous calculons la transmission de la structure graphite et nous mettons en évidence le rôle fondamental du couplage avec les modes extérieurs. Nous étudions l'apparition de modes permis dans la bande interdite grâce à l'introduction de défauts dans la périodicité. Enfin, nous discutons les propriétés des opales constituées de micro-billes de silice auto-organisées, qui sont très prometteuses pour la fabrication de cristaux photoniques tridimensionnels.

  19. Closing the stop gap

    Energy Technology Data Exchange (ETDEWEB)

    Czakon, Michal [RWTH Aachen Univ. (Germany). Inst. fuer Theoretische Teilchnphysik und Kosmologie; Mitov, Alexander [Univ. of Cambridge (United Kingdom). Cavendish Lab.; Papucci, Michele [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; Ruderman, Joshua T. [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; New York Univ., NY (United States). Center for Cosmology and Particle Physics; Weiler, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); CERN - European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.

    2014-07-15

    Light stops are a hallmark of the most natural realizations of weak-scale supersymmetry. While stops have been extensively searched for, there remain open gaps around and below the top mass, due to similarities of stop and top signals with current statistics. We propose a new fast-track avenue to improve light stop searches for R-parity conserving supersymmetry, by comparing top cross section measurements to the theoretical prediction. Stop masses below ∝180 GeV can now be ruled out for a light neutralino. The possibility of a stop signal contaminating the top mass measurement is also briefly addressed.

  20. Mind the Gap

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While a growing number of Chinese people are enjoying the benefits brought by economic reform and social development, some are being left behind. The divide between the rich and the poor is widening in China, resulting in an increasingly dissatisfied populace. Some argue that a wealth gap is not a big deal in a market economy and that the problem in China has been exaggerated. But in an article published by China Economic Times, Wu Zhongmin, a sociology professor at the Central Party School of the Commun...

  1. Incentive Model Based on Cooperative Relationship in Sustainable Construction Projects

    Directory of Open Access Journals (Sweden)

    Guangdong Wu

    2017-07-01

    Full Text Available Considering the cooperative relationship between owners and contractors in sustainable construction projects, as well as the synergistic effects created by cooperative behaviors, a cooperative incentive model was developed using game theory. The model was formulated and analyzed under both non-moral hazard and moral hazard situations. Then, a numerical simulation and example were proposed to verify the conclusions derived from the model. The results showed that the synergistic effect increases the input intensity of one party’s resource transfer into the increase of marginal utility of the other party, thus the owner and contractor are willing to enhance their levels of effort. One party’s optimal benefit allocation coefficient is positively affected by its own output efficiency, and negatively affected by the other party’s output efficiency. The effort level and expected benefits of the owner and contractor can be improved by enhancing the cooperative relationship between the two parties, as well as enhancing the net benefits of a sustainable construction project. The synergistic effect cannot lower the negative effect of moral hazard behaviors during the implementation of sustainable construction projects. Conversely, the higher levels of the cooperative relationship, the wider the gaps amongst the optimal values under both non-moral hazard and moral hazard situations for the levels of effort, expected benefits and net project benefits. Since few studies to date have emphasized the effects of cooperative relationship on sustainable construction projects, this study constructed a game-based incentive model to bridge the gaps. This study contributes significant theoretical and practical insights into the management of cooperation amongst stakeholders, and into the enhancement of the overall benefits of sustainable construction projects.

  2. Board affiliation and pay gap

    Institute of Scientific and Technical Information of China (English)

    Shenglan; Chen; Hui; Ma; Danlu; Bu

    2014-01-01

    This paper examines the effects of board affiliation on the corporate pay gap.Using a sample of Chinese listed firms from 2005 to 2011, we find that boards with a greater presence of directors appointed by block shareholders have lower pay gaps. Furthermore, the governance effects of board affiliation with and without pay are distinguished. The empirical results show that board affiliation without pay is negatively related to the pay gap, while board affiliation with pay is positively related to the pay gap. Overall, the results shed light on how block shareholders affect their companies’ pay gaps through board affiliation.

  3. Structural Basis of Cooperative Ligand Binding by the Glycine Riboswitch

    Energy Technology Data Exchange (ETDEWEB)

    E Butler; J Wang; Y Xiong; S Strobel

    2011-12-31

    The glycine riboswitch regulates gene expression through the cooperative recognition of its amino acid ligand by a tandem pair of aptamers. A 3.6 {angstrom} crystal structure of the tandem riboswitch from the glycine permease operon of Fusobacterium nucleatum reveals the glycine binding sites and an extensive network of interactions, largely mediated by asymmetric A-minor contacts, that serve to communicate ligand binding status between the aptamers. These interactions provide a structural basis for how the glycine riboswitch cooperatively regulates gene expression.

  4. Gap Task Force

    CERN Multimedia

    Lissuaer, D

    One of the more congested areas in the ATLAS detector is the GAP region (the area between the Barrel Calorimeter and the End Cap calorimeter) where Inner Detector services, LAr Services and some Tile services all must co-habitat in a very limited area. It has been clear for some time that the space in the GAP region is not sufficient to accommodate all that is needed. In the last few month additional problems of routing all the services to Z=0 have been encountered due to the very limited space between the Tile Calorimeter and the first layer of Muon chambers. The Technical Management Board (TMB) and the Executive Board (EB) decided in the middle of March to establish a Task Force to look at this problem and come up with a solution within well-specified guidelines. The task force consisted of experts from the ID, Muon, Liquid Argon and Tile systems in addition to experts from the Technical Coordination team and the Physics coordinator. The task force held many meetings and in general there were some very l...

  5. Prospects of ASEAN Legal Cooperation

    OpenAIRE

    Agus Riyanto

    2016-01-01

    Association of Southeast Asian Nations (ASEAN) is a regional organization in the countries of Southeast Asia established in Bangkok, Thailand, on August 8, 1967 (the Bangkok Declaration) by Indonesia, Malaysia, Philippines, Singapore, and Thailand. One form of cooperation that could further encourage the establishment of ASEAN's goal was legal cooperation. This was because, this cooperation could further strengthen cooperation in politics, economy, social and culture in Southeast Asia. ...

  6. The Politics of Achievement Gaps

    DEFF Research Database (Denmark)

    Valant, J.; Newark, D. A.

    2016-01-01

    on achievement gaps have received little attention from researchers, despite playing an important role in shaping policymakers’ behaviors. Drawing on randomized experiments with a nationally representative sample of adults, we explore the public’s beliefs about test score gaps and its support for gap......-closing initiatives. We find that Americans are more concerned about—and more supportive of proposals to close—wealth-based achievement gaps than Black-White or Hispanic-White gaps. Americans also explain the causes of wealth-based gaps more readily. © 2016 AERA.......For decades, researchers have documented large differences in average test scores between minority and White students and between poor and wealthy students. These gaps are a focal point of reformers’ and policymakers’ efforts to address educational inequities. However, the U.S. public’s views...

  7. Enhancing international technology cooperation for climate change mitigation. Lessons from an electromobility case study

    Energy Technology Data Exchange (ETDEWEB)

    Bhasin, Shikha

    2014-07-01

    As a global agreement on climate mitigation and absolute emissions reductions remains grid-locked, this paper assesses whether the prospects for international technology cooperation in low-carbon sectors can be improved. It analyses the case of international cooperation on electric vehicle technologies to elaborate on the trade-offs that cooperation such as this inherently attempts to balance- national growth objectives of industrial and technology development versus the global goods benefit of reducing greenhouse gas (GHG) emissions. It focuses on bilateral German-Chinese programmes for electric vehicle development, as well as multilateral platforms on low-carbon technology cooperation related to electric vehicles. Based on insights from these cases studies, this paper ultimately provides policy recommendations to address gaps in international technology cooperation at a bilateral level for ongoing German-Chinese engagement on electric vehicles; and at a multilateral level with a focus on the emerging technology cooperation framework of the United Nations Framework Convention on Climate Change (UNFCCC).

  8. Cooperative Learning in Elementary Schools

    Science.gov (United States)

    Slavin, Robert E.

    2015-01-01

    Cooperative learning refers to instructional methods in which students work in small groups to help each other learn. Although cooperative learning methods are used for different age groups, they are particularly popular in elementary (primary) schools. This article discusses methods and theoretical perspectives on cooperative learning for the…

  9. Cooperative Learning: Developments in Research

    Science.gov (United States)

    Gillies, Robyn M.

    2014-01-01

    Cooperative learning is widely recognized as a pedagogical practice that promotes socialization and learning among students from kindergarten through to college level and across different subject areas. Cooperative learning involves students working together to achieve common goals or complete group tasks. Interest in cooperative learning has…

  10. Seeking Cooperation in Green Economy

    Institute of Scientific and Technical Information of China (English)

    Wan Jifei

    2010-01-01

    @@ On May28,the 2 n d China-South Korea Green Economic Cooperation Forum,sponsored by CCPIT and KCCI,was held in Seoul,South Korea. The subjects tallked about at the forum were "New Recycle Energy Cooperation Plan and Strategy"and Cooperation Plan and Strategy in Green Industries"etc

  11. COOPERATIVE LEARNING IN LARGE CLASSES

    Institute of Scientific and Technical Information of China (English)

    GuoXiangju

    2004-01-01

    Teaching college English in large classes is a new challenge to teachers. To meet this challenge, the strategy of cooperative learning is practicable. This paper introduces cooperative learning and describes the experiment results, which prove the advantages of cooperative learning over competitive learning or individualistic learning.

  12. The governance of cooperative societies

    Directory of Open Access Journals (Sweden)

    Yaiza Juanes Sobradillo

    2005-12-01

    Full Text Available The present work aims to expose the appropriate legislation for cooperative societies to which Article 129 of the Spanish Constitution refers, deepen the analysis of the organs of management and control based on the Spanish and Basque Laws on Cooperatives and the Statute for the European Cooperative Societies.

  13. Cooperation in Networks and Scheduling

    NARCIS (Netherlands)

    van Velzen, S.

    2005-01-01

    This thesis deals with various models of cooperation in networks and scheduling. The main focus is how the benefits of this cooperation should be divided among the participating individuals. A major part of this analysis is concerned with stability of the cooperation. In addition, allocation rules a

  14. Gender and Cooperation in Children

    DEFF Research Database (Denmark)

    Cardenas, Juan-Camilo; Dreber, Anna; Essen, Emma von;

    2014-01-01

    between Colombia and Sweden overall. However, Colombian girls cooperate less than Swedish girls. We also find indications that girls in Colombia are less cooperative than boys. Finally, there is also a tendency for children to be more cooperative with boys than with girls on average....

  15. Covering All the Bases in Genetics: Simple Shorthands and Diagrams for Teaching Base Pairing to Biology Undergraduates

    Directory of Open Access Journals (Sweden)

    Sergei Kuchin

    2011-03-01

    Full Text Available Explaining base pairing is an important element in teaching undergraduate genetics. I propose a teaching approach that aims to close the gap between the mantra “A pairs with T, and G pairs with C” and the “intimidating” chemical diagrams. The approach offers a set of simple “shorthands” for the key bases that can be used to quickly deduce all canonical and wobble pairs that the students need to know. The approach can be further developed to analyze mutagenic mismatch pairing.

  16. Importance of interlayer pair tunneling: A variational perspective

    Energy Technology Data Exchange (ETDEWEB)

    Medhi, Amal, E-mail: amedhi@iitg.ernet.i [Department of Basic Sciences and Social Sciences, North-Eastern Hill University, Shillong 793 022 (India); Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781 039 (India); Basu, Saurabh, E-mail: saurabh@iitg.ernet.i [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781 039 (India)

    2011-01-15

    We study the effect of interlayer pair tunneling in a bilayer superconductor where each layer is described by a two dimensional t-J model and the two layers are connected by the Josephson pair tunneling term. We study this model using a grand canonical variational Monte Carlo (GVMC) method, for which we develop a new algorithm to perform Monte Carlo simulation of a system with fluctuating particle number. The variational wavefunction is taken to be the product of two Gutzwiller projected d-wave BCS wavefunctions with variable particle densities, one for each layer. We calculate the energy of the above state as a function of the d-wave superconducting gap parameter, {Delta}. We find that the interlayer pair tunneling energy, E{sub perpendicular} shows interesting variation with {Delta}. E{sub perpendicular} tends to enhance the optimal value of {Delta}, thereby the superconducting pairing. However the magnitude of the tunneling energy is found to be too small to have any appreciable effect on the physical properties. While the result is supported by early experiments and hence may appear known to the community, the current work presents a new approach to the problem and confirms the diminished role of interlayer pair tunneling by directly calculating its contribution to superconducting condensation energy.

  17. Small Multiples with Gaps.

    Science.gov (United States)

    Meulemans, Wouter; Dykes, Jason; Slingsby, Aidan; Turkay, Cagatay; Wood, Jo

    2017-01-01

    Small multiples enable comparison by providing different views of a single data set in a dense and aligned manner. A common frame defines each view, which varies based upon values of a conditioning variable. An increasingly popular use of this technique is to project two-dimensional locations into a gridded space (e.g. grid maps), using the underlying distribution both as the conditioning variable and to determine the grid layout. Using whitespace in this layout has the potential to carry information, especially in a geographic context. Yet, the effects of doing so on the spatial properties of the original units are not understood. We explore the design space offered by such small multiples with gaps. We do so by constructing a comprehensive suite of metrics that capture properties of the layout used to arrange the small multiples for comparison (e.g. compactness and alignment) and the preservation of the original data (e.g. distance, topology and shape). We study these metrics in geographic data sets with varying properties and numbers of gaps. We use simulated annealing to optimize for each metric and measure the effects on the others. To explore these effects systematically, we take a new approach, developing a system to visualize this design space using a set of interactive matrices. We find that adding small amounts of whitespace to small multiple arrays improves some of the characteristics of 2D layouts, such as shape, distance and direction. This comes at the cost of other metrics, such as the retention of topology. Effects vary according to the input maps, with degree of variation in size of input regions found to be a factor. Optima exist for particular metrics in many cases, but at different amounts of whitespace for different maps. We suggest multiple metrics be used in optimized layouts, finding topology to be a primary factor in existing manually-crafted solutions, followed by a trade-off between shape and displacement. But the rich range of possible

  18. Observation of particle pairing in a two-dimensional plasma crystal

    CERN Document Server

    Zhdanov, S K; Nosenko, V; Thomas, H M; Morfill, G E

    2013-01-01

    The observation is presented of naturally occurring pairing of particles and their cooperative drift in a two-dimensional plasma crystal. A single layer of plastic microspheres was suspended in the plasma sheath of a capacitively coupled rf discharge in argon at a low pressure of 1 Pa. The particle dynamics were studied by combining the top-view and side-view imaging of the suspension. Cross analysis of the particle trajectories allowed us to identify naturally occurring metastable pairs of particles. The lifetime of pairs was long enough for their reliable identification.

  19. Formation of Singlet Fermion Pairs in the Dilute Gas of Boson-Fermion Mixture

    Directory of Open Access Journals (Sweden)

    Minasyan V.

    2010-10-01

    Full Text Available We argue the formation of a free neutron spinless pairs in a liquid helium -dilute neutron gas mixture. We show that the term, of the interaction between the excitations of the Bose gas and the density modes of the neutron, meditate an attractive interaction via the neutron modes, which in turn leads to a bound state on a spinless neutron pair. Due to presented theoretical approach, we prove that the electron pairs in superconductivity could be discovered by Frölich earlier then it was made by the Cooper.

  20. Formation of Singlet Fermion Pairs in the Dilute Gas of Boson-Fermion Mixture

    Directory of Open Access Journals (Sweden)

    Samoilov V.

    2010-10-01

    Full Text Available We argue the formation of a free neutron spinless pairs in a liquid helium -dilute neutron gas mixture. We show that the term, of the interaction between the excitations of the Bose gas and the density modes of the neutron, meditate an attractive interaction via the neutron modes, which in turn leads to a bound state on a spinless neutron pair. Due to presented theoretical approach, we prove that the electron pairs in superconductivity could be discovered by Froelich earlier then it was made by the Cooper.

  1. Evidence for pair correlation effects in heavy ion reactions

    CERN Document Server

    Auditore, L; D'Amico, V; De Pasquale, D; Trifiró, A; Trimarchi, M; Italiano, A

    2003-01-01

    The study of the sup 1 sup 2 C( sup 1 sup 4 N, sup 1 sup 4 N) sup 1 sup 2 C reaction was performed at 28 and 35 MeV beam energies. The results were analyzed in the frame of the EFRDWBA (Exact-Finite-Range Distorted Wave Born Approximation) assuming the simultaneous and sequential transfer of a np pair. The angular distributions, fairly reproduced in the first case, confirm the validity of the generalized BCS (Bardeen-Cooper-Schrieffer) theory to explain this behaviour. Moreover, this process could be regarded as a possible Nuclear Josephson Effect. (author)

  2. Paired structures in knowledge representation

    DEFF Research Database (Denmark)

    Montero, J.; Bustince, H.; Franco de los Ríos, Camilo;

    2016-01-01

    In this position paper we propose a consistent and unifying view to all those basic knowledge representation models that are based on the existence of two somehow opposite fuzzy concepts. A number of these basic models can be found in fuzzy logic and multi-valued logic literature. Here it is clai......In this position paper we propose a consistent and unifying view to all those basic knowledge representation models that are based on the existence of two somehow opposite fuzzy concepts. A number of these basic models can be found in fuzzy logic and multi-valued logic literature. Here...... of paired structures, generated from two paired concepts together with their associated neutrality, all of them to be modeled as fuzzy sets. In this way, paired structures can be viewed as a standard basic model from which different models arise. This unifying view should therefore allow a deeper analysis...

  3. Organometallic frustrated Lewis pair chemistry.

    Science.gov (United States)

    Erker, Gerhard

    2011-08-07

    Frustrated Lewis pairs are playing an increasingly important role in organometallic chemistry. Examples are presented and discussed where organometallic systems themselves serve as the Lewis base or Lewis acid components in frustrated Lewis pair chemistry, mostly through their attached functional groups. Activation of dihydrogen takes place easily in many of these systems. This may lead to the generation of novel catalyst systems but also in many cases to the occurrence of specific reactions at the periphery of the organometallic frameworks. Increasingly, FLP reactions are used to carry out functional group conversions in organometallic systems under mild reaction conditions. The limits of typical FLP reactivity are explored with selected organometallic examples, a discussion that points toward new developments, such as the discovery of facile new 1,1-carboboration reactions. Learning more and more about the broad spectrum of frustrated Lewis pair chemistry helps us to find novel reactions and applications.

  4. Cooperative method development

    DEFF Research Database (Denmark)

    Dittrich, Yvonne; Rönkkö, Kari; Eriksson, Jeanette;

    2008-01-01

    research is not easily combined with the improvement orientation of an engineering discipline. During the last 6 years, we have applied an approach we call `cooperative method development', which combines qualitative social science fieldwork, with problem-oriented method, technique and process improvement....... The action research based approach focusing on shop floor software development practices allows an understanding of how contextual contingencies influence the deployment and applicability of methods, processes and techniques. This article summarizes the experiences and discusses the further development......The development of methods tools and process improvements is best to be based on the understanding of the development practice to be supported. Qualitative research has been proposed as a method for understanding the social and cooperative aspects of software development. However, qualitative...

  5. Cooperative Learning i voksenundervisningen

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne

    Nationalt Center for Kompetenceudvikling har evalueret undervisningsmetoden Cooperative Learning i voksenundervisningen og dokumenteret positive effekter på oplevelsen af samarbejde og på lærere og kursisters engagement - men har ikke kunnet påvise systematiske positive effekter af metoden på...... kursisters frafald, fravær og karakterer. Projektet har afprøvet og videreudviklet den pædagogiske metode Cooperative Learning (CL) i en dansk virkelighed og mere specifikt i forhold til VUC'ernes nye kursistgrupper med det overordnede mål at øge gennemførslen markant og målbart ved at anvende og udvikle en...

  6. Growth, Cooperation And Prosperity

    Institute of Scientific and Technical Information of China (English)

    YAN WEI

    2010-01-01

    @@ Chinese Vice President Xi Jinping called for strengthened cconomic,political and cultural ties with Bangladesh,Laos,New Zealand and Australia during his visits to these countries from June 14-24. In a speech at a trade forum in Canberra,Xi suggested China and Australia deepen cooperation in energy and resources.The two countries' governments and companies should work together to build "'long-term and stable"relations for trade and investment in these fields.

  7. Automated Cooperative Trajectories

    Science.gov (United States)

    Hanson, Curt; Pahle, Joseph; Brown, Nelson

    2015-01-01

    This presentation is an overview of the Automated Cooperative Trajectories project. An introduction to the phenomena of wake vortices is given, along with a summary of past research into the possibility of extracting energy from the wake by flying close parallel trajectories. Challenges and barriers to adoption of civilian automatic wake surfing technology are identified. A hardware-in-the-loop simulation is described that will support future research. Finally, a roadmap for future research and technology transition is proposed.

  8. Decentralized Cooperative Networking

    Science.gov (United States)

    2012-02-24

    protocols (such as DSR and AODV ) where route request (RREQ) and route reply (RREP) control packets are transmitted via SISO transmissions. Then, specific... routing . To make the routing protocol scalable, M-group Dis-STBC is applied, and an analysis of the cooperative transmission range is provided to guide...higher throughput in comparison to a Single-Input-Single-Output (SISO) based routing protocol . On the other hand, because LACR is designed to

  9. Crisis-Driven Cooperation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Not hit as badly as the West, East Asian and Southeast Asian countries grapple with the financial crisis from a long-term perspective Although Thailand postponed at the last minute the annual summits of East Asian and Southeast Asian leaders scheduled on April 11-12, regional cooperation will continue to forge ahead with full vigor, even more so in the context of the global financial crisis, said Chinese international studies experts.

  10. Pioneers in Cooperation (selection)

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ Project-oriented cooperation within the framework of the CAS-MPSagreement began in the early 1980s. Its methods differed according to scientific needs and included workshops and seminars, field research, overland expeditions, exchanges of materials and samples, and the training of young scientists and engineers. The German Research Foundation and the National Natural Science Foundation of China provided special funding for many of these projects.

  11. Working for Better Cooperation

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China and the United States seek to iron out differences at the recent Strategic and Economic Dialogue Despite disputes over trade,exchange rates and the investment climate,China and the United States are striving to promote cooperation through dialogue,as the two countries become increasingly dependent on each other and benefit substantially from each other’s development,said Chinese officials and scholars.

  12. 75 FR 10319 - Cooper Tools-Sumter, Cooper Tools Divisions, a Subsidiary of Cooper Industries, Inc., Including...

    Science.gov (United States)

    2010-03-05

    ...] Cooper Tools--Sumter, Cooper Tools Divisions, a Subsidiary of Cooper Industries, Inc., Including On-Site... Worker Adjustment Assistance on January 26, 2010, applicable to workers of Cooper Tools--Sumter, Cooper Tools Division, a subsidiary of Cooper Industries, Inc., including on-site leased workers from...

  13. Gaps in Political Interest

    DEFF Research Database (Denmark)

    Robison, Joshua

    2015-01-01

    sought to measure respondents’ general interest in politics by asking them how often they follow public affairs. In this article, we uncover novel sources of measurement error concerning this question. We first show that other nationally representative surveys that frequently use this item deliver......Political interest fundamentally influences political behavior, knowledge, and persuasion (Brady, Verba, & Schlozman, 1995; Delli Carpini & Keeter, 1996; Luskin, 1990; Zukin, Andolina, Keeter, Jenkins, & Delli Carpini, 2006). Since the early 1960s, the American National Election Studies (ANES) has...... drastically higher estimates of mass interest. We then use a survey experiment included on a wave of the ANES’ Evaluating Government and Society Surveys (EGSS) to explore the influence of question order in explaining this systemic gap in survey results. We show that placing batteries of political...

  14. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques......, rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps......, which, though independent of each other, are determined by questions of the ongoing design process. The first step consists of an abstract or subjective research phase; in the second step the findings are transferred into dynamic spatial structures. Later, the detected qualities are used to develop...

  15. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques......, rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps...... architectural projects can be discussed; in addition, a competent monitoring of the process and outcome of innovative and efficient design strategies in architectural and pedagogical aspect is included....

  16. The Gap-Tpc

    Science.gov (United States)

    Rossi, B.; Anastasio, A.; Boiano, A.; Catalanotti, S.; Cocco, A. G.; Covone, G.; Di Meo, P.; Longo, G.; Vanzanella, A.; Walker, S.; Wang, H.; Wang, Y.; Fiorillo, G.

    2016-02-01

    Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency.

  17. The GAP-TPC

    CERN Document Server

    Rossi, B; Boiano, A; Catalanotti, S; Cocco, A G; Covone, G; Di Meo, P; Longo, G; Vanzanella, A; Walker, S; Wang, H; Wang, Y; Fiorillo, G

    2016-01-01

    Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency

  18. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques...... architectural projects can be discussed; in addition, a competent monitoring of the process and outcome of innovative and efficient design strategies in architectural and pedagogical aspect is included......., rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps...

  19. Cooperative Mobile Web Browsing

    Directory of Open Access Journals (Sweden)

    Zhang Q

    2009-01-01

    Full Text Available This paper advocates a novel approach for mobile web browsing based on cooperation among wireless devices within close proximity operating in a cellular environment. In the actual state of the art, mobile phones can access the web using different cellular technologies. However, the supported data rates are not sufficient to cope with the ever increasing traffic requirements resulting from advanced and rich content services. Extending the state of the art, higher data rates can only be achieved by increasing complexity, cost, and energy consumption of mobile phones. In contrast to the linear extension of current technology, we propose a novel architecture where mobile phones are grouped together in clusters, using a short-range communication such as Bluetooth, sharing, and accumulating their cellular capacity. The accumulated data rate resulting from collaborative interactions over short-range links can then be used for cooperative mobile web browsing. By implementing the cooperative web browsing on commercial mobile phones, it will be shown that better performance is achieved in terms of increased data rate and therefore reduced access times, resulting in a significantly enhanced web browsing user experience on mobile phones.

  20. Exlusive charmed meson pair production

    CERN Document Server

    Berezhnoy, A V

    2004-01-01

    The experimental data of BELLE Collaboration on the exclusive charmed meson pair production in the process of monophotonic $e^+e^-$-annihilation ($e^+e^-\\to \\gamma^* \\to D\\bar D$) has been studied. It has been shown that these data is described satisfactorily in the frame work of constituent quark model. Our studies have demonstrated that the central production process $e^+e^-\\to e^+e^-\\gamma\\gamma \\to e^+e^-D\\bar D +X$ and the process of monophotonic $e^+e^-$-annihilation yield comparable numbers of the charmed meson pairs.

  1. Instantons in lepton pair production

    Energy Technology Data Exchange (ETDEWEB)

    Brandenburg, A.; Ringwald, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Utermann, A. [Vrije Univ., Amsterdam (Netherlands). Dept. of Physics and Astronomy

    2006-05-15

    We consider QCD instanton-induced contributions to lepton pair production in hadron-hadron collisions. We relate these contributions to those known from deep inelastic scattering and demonstrate that they can be calculated reliably for sufficiently large momentum transfer. We observe that the instanton contribution to the angular distribution of the lepton pairs at finite momentum transfer strongly violates the Lam-Tung relation - a relation between coefficient functions of the angular distribution which is valid within the framework of ordinary perturbation theory. The drastic violation of this relation, as seen in experimental data, might be related to such instanton-induced effects. (Orig.)

  2. Selfish strategies develop in social problem situations in chimpanzee (Pan troglodytes) mother–infant pairs.

    Science.gov (United States)

    Yamamoto, Shinya; Tanaka, Masayuki

    2009-10-01

    Humans employ various strategies, including selfish and altruistic strategies, depending on the situation.In order to examine whether non-human animals show such flexibility or not, we analyzed chimpanzees' selfish and cooperative behavior in two types of social problem situations.In this study, we tested chimpanzee mother–infant pairs in two adjacent booths, each equipped with a vending machine. When a token was inserted into a vending machine, the vending machine delivered food rewards to the adjacent booth. In experiment 1, a partition between the two booths was open. In experiment 2, the partition was closed and a mother and her infant were placed in separate booths, so that reciprocal cooperation was essential for them to receive rewards. The participants did not cooperate reciprocally in either experiment. In experiment 1, the chimpanzees developed selfish tactics to get rewards and changed their tactics flexibly according to the partner's behaviors. In experiment 2, in which they could not receive rewards without cooperation, they stopped altogether inserting tokens. In both cases, the infants stopped cooperating first. These findings support the idea that chimpanzees are primarily competitive rather than cooperative. Chimpanzees'high social intelligence might be demonstrated in the flexibility of their selfish tactics, but not in the form of reciprocal cooperation at least when food is involved. We suggest that the failure to establish reciprocal cooperation was due to the social relationship between the mother and her infant, which was characterized by infant's privilege and mother's tolerance.

  3. A Combinational Perspective in Stimulating Cooperation in Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Mahshid Rahnamay-Naeini; Masoud Sabaei

    2011-01-01

    In wireless ad hoc networks cooperation among nodes cannot always be assumed since nodes with limited resources and different owners are capable of making independent decisions. Cooperation problems in topology control and packet forwarding tasks have been mostly studied separately but these two tasks are not independent. Considering a joint cooperation problem by taking into account dependencies between tasks will result in more reliable and efficient networks. In this paper topology control definition is extended to cover cooperation problem in both packet forwarding and topology control in a single problem. In this definition nodes have to adjust their transmission power and decide on their relay role. This paper models the interactions of nodes as a potential game with two-dimensional utility function. The presented model, named TCFORCE (Topology Control packet FORwarding Cooperation Enforcement), preserves the network connectivity and reduces the energy consumption by providing cooperative paths between all pairs of nodes in the network.

  4. Temperature-dependent nuclear moment of inertia including neutron-proton pairing correlations

    Energy Technology Data Exchange (ETDEWEB)

    Ami, Ismahane [Institut des Sciences et de la Technologie, Universite Yahia Fares de Medea, Ain-D heb, 26000 Medea (Algeria); Laboratoire de Physique Theorique, Faculte de Physique, USTHB, BP32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Belabbas, Mohamed [Faculte des Sciences et des Sciences de l' Ingenieur, Universite Hassiba Ben Bouali, BP151, 02000 Chlef (Algeria); Benhamouda, Naziha [Laboratoire de Physique Theorique, Faculte de Physique, USTHB, BP32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Fellah, Mohamed; Allal, Nassima-Hosni [Laboratoire de Physique Theorique, Faculte de Physique, USTHB, BP32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Centre de Recherche Nucleaire d Alger, COMENA, BP 399 Alger-Gare, Alger (Algeria)

    2009-07-01

    Expressions of the temperature-dependent parallel and perpendicular nuclear moments of inertia including neutron-proton pairing correlations have been established. The latter have been derived using the cranking method as well as the isovector temperature-dependent gap equations. They generalize the expressions of the usual finite-temperature BCS (FTBCS) method. The model has been applied to the schematic Richardson model. The obtained results are compared to those of the usual FTBCS approach for the pairing between like-particles.

  5. On p-Wave Pairing Superconductivity under Cubic Symmetry : Condensed Matter and Statistical Physics

    OpenAIRE

    Masa-aki, OZAKI; Kazushige, MACHIDA; Tetsuo, OHMI; Department of Physics, Kyoto University

    1985-01-01

    A group theoretical classification of p-wave pairing superconducting states is made for a system with cubic crystalline symmetry in the absence of the spin-orbit coupling. The 15 inert p-pairing states which make the Ginzburg-Landau free energy stationary are enumerated and characterized, indicating that the energy gap vanishes along lines on the Fermi surface in some of those states. This is contrasted with the strong spin-orbit coupling case by others.

  6. Coalitions in Cooperative Wireless Networks

    CERN Document Server

    Mathur, Suhas; Mandayam, Narayan B

    2008-01-01

    Cooperation between rational users in wireless networks is studied using coalitional game theory. Using the rate achieved by a user as its utility, it is shown that the stable coalition structure, i.e., set of coalitions from which users have no incentives to defect, depends on the manner in which the rate gains are apportioned among the cooperating users. Specifically, the stability of the grand coalition (GC), i.e., the coalition of all users, is studied. Transmitter and receiver cooperation in an interference channel (IC) are studied as illustrative cooperative models to determine the stable coalitions for both flexible (transferable) and fixed (non-transferable) apportioning schemes. It is shown that the stable sum-rate optimal coalition when only receivers cooperate by jointly decoding (transferable) is the GC. The stability of the GC depends on the detector when receivers cooperate using linear multiuser detectors (non-transferable). Transmitter cooperation is studied assuming that all receivers coopera...

  7. The Adaptation Finance Gap Report

    DEFF Research Database (Denmark)

    UNEP’s Adaptation Gap Report series focuses on Finance, Technology and Knowledge gaps in climate change adaptation. It compliments the Emissions Gap Report series, and explores the implications of failing to close the emissions gap. The report builds on a 2014 assessment by the United Nations...... Environment Programme (UNEP), which laid out the concept of ‘adaptation gaps’ and outlined three such gaps: technology, finance and knowledge. The 2016 Adaptation Gap Report assesses the difference between the financial costs of adapting to climate change in developing countries and the amount of money...... actually available to meet these costs – a difference known as the “adaptation finance gap”. Like the 2014 report, the 2016 report focuses on developing countries, where adaptation capacity is often the lowest and needs the highest, and concentrates on the period up to 2050. The report identifies trends...

  8. Electron pair creation by photons

    NARCIS (Netherlands)

    Holtwijk, Theodoor

    1960-01-01

    In our experiment on the creation of electron pairs a 5 MeV betatron was used as radiation source and a cloud chamber (with magnetic field) was used as detection instrument. The experimental arrangement is described in section 2.1. The cloud chamber was of the overcompression type so that the recove

  9. Pairs of dual periodic frames

    DEFF Research Database (Denmark)

    Christensen, Ole; Goh, Say Song

    2012-01-01

    is needed. The purpose of the present paper is to provide constructions of dual pairs of frames in the setting of the Hilbert space of periodic functions L2(0,2π). The frames constructed are given explicitly as trigonometric polynomials, which allows for an efficient calculation of the coefficients...

  10. Electron pair creation by photons

    NARCIS (Netherlands)

    Holtwijk, Theodoor

    1960-01-01

    In our experiment on the creation of electron pairs a 5 MeV betatron was used as radiation source and a cloud chamber (with magnetic field) was used as detection instrument. The experimental arrangement is described in section 2.1. The cloud chamber was of the overcompression type so that the recove

  11. The use of surface layer with boron in friction pairs lubricated by engine oils

    Science.gov (United States)

    Szczypiński-Sala, W.; Lubas, J.

    2016-09-01

    The aim of the present work is to determine the influence of surface layers with boron and engine oil on the processes of friction and wear in friction pairs. The ring samples with borided surface layer cooperated under test conditions with counterparts made with CuPb30 and AlSn20 bearing alloys. During the tests, the friction pairs were lubricated with 15W/40 Lotos mineral oil and 5W/40 Lotos synthetic oil. The lubrication of friction area with Lotos mineral oil causes the reduction of the friction force, the temperature in the friction area and the wear of the bearing alloys under study, whereas the lubrication with Lotos synthetic oil reduces the changes in the geometrical structure of the cooperating friction pair elements. Lubrication of the friction area in the start-up phase of the friction pair by mineral oil causes faster stabilization of the friction conditions in the contact area than in the cause of lubrication of the friction pair by synthetic oil. The intensity of wear of the AlSn20 bearing alloy cooperating with the borided surface layer is three times smaller than the intensity of use of the CuPb30 alloy bearing.

  12. Gender differences in cooperation: experimental evidence on high school students.

    Directory of Open Access Journals (Sweden)

    J Alberto Molina

    Full Text Available The emergence of cooperation among unrelated human subjects is a long-standing conundrum that has been amply studied both theoretically and experimentally. Within the question, a less explored issue relates to the gender dependence of cooperation, which can be traced back to Darwin, who stated that "women are less selfish but men are more competitive". Indeed, gender has been shown to be relevant in several game theoretical paradigms of social cooperativeness, including prisoner's dilemma, snowdrift and ultimatum/dictator games, but there is no consensus as to which gender is more cooperative. We here contribute to this literature by analyzing the role of gender in a repeated Prisoners' Dilemma played by Spanish high-school students in both a square lattice and a heterogeneous network. While the experiment was conducted to shed light on the influence of networks on the emergence of cooperation, we benefit from the availability of a large dataset of more 1200 participants. We applied different standard econometric techniques to this dataset, including Ordinary Least Squares and Linear Probability models including random effects. All our analyses indicate that being male is negatively associated with the level of cooperation, this association being statistically significant at standard levels. We also obtain a gender difference in the level of cooperation when we control for the unobserved heterogeneity of individuals, which indicates that the gender gap in cooperation favoring female students is present after netting out this effect from other socio-demographics factors not controlled for in the experiment, and from gender differences in risk, social and competitive preferences.

  13. Gender differences in cooperation: experimental evidence on high school students.

    Science.gov (United States)

    Molina, J Alberto; Giménez-Nadal, J Ignacio; Cuesta, José A; Gracia-Lazaro, Carlos; Moreno, Yamir; Sanchez, Angel

    2013-01-01

    The emergence of cooperation among unrelated human subjects is a long-standing conundrum that has been amply studied both theoretically and experimentally. Within the question, a less explored issue relates to the gender dependence of cooperation, which can be traced back to Darwin, who stated that "women are less selfish but men are more competitive". Indeed, gender has been shown to be relevant in several game theoretical paradigms of social cooperativeness, including prisoner's dilemma, snowdrift and ultimatum/dictator games, but there is no consensus as to which gender is more cooperative. We here contribute to this literature by analyzing the role of gender in a repeated Prisoners' Dilemma played by Spanish high-school students in both a square lattice and a heterogeneous network. While the experiment was conducted to shed light on the influence of networks on the emergence of cooperation, we benefit from the availability of a large dataset of more 1200 participants. We applied different standard econometric techniques to this dataset, including Ordinary Least Squares and Linear Probability models including random effects. All our analyses indicate that being male is negatively associated with the level of cooperation, this association being statistically significant at standard levels. We also obtain a gender difference in the level of cooperation when we control for the unobserved heterogeneity of individuals, which indicates that the gender gap in cooperation favoring female students is present after netting out this effect from other socio-demographics factors not controlled for in the experiment, and from gender differences in risk, social and competitive preferences.

  14. Superconductivity in repulsively interacting fermions on a diamond chain: Flat-band-induced pairing

    Science.gov (United States)

    Kobayashi, Keita; Okumura, Masahiko; Yamada, Susumu; Machida, Masahiko; Aoki, Hideo

    2016-12-01

    To explore whether a flat-band system can accommodate superconductivity, we consider repulsively interacting fermions on the diamond chain, a simplest possible quasi-one-dimensional system that contains a flat band. Exact diagonalization and the density-matrix renormalization group are used to show that we have a significant binding energy of a Cooper pair with a long-tailed pair-pair correlation in real space when the total band filling is slightly below 1/3, where a filled dispersive band interacts with the flat band that is empty but close to EF. Pairs selectively formed across the outer sites of the diamond chain are responsible for the pairing correlation. At exactly 1/3-filling an insulating phase emerges, where the entanglement spectrum indicates the particles on the outer sites are highly entangled and topological. These come from a peculiarity of the flat band in which "Wannier orbits" are not orthogonalizable.

  15. Understanding the Tax Gap1

    OpenAIRE

    Mazur, Mark J.; Plumley, Alan H.

    2007-01-01

    The Tax Gap is defined as the difference between the amount of tax imposed by the Tax Code and the amount that is reported and paid with timely filed returns. For the federal government, the gross tax gap is estimated at $345 billion for Tax Year 2001 (after the collection of late and enforced payments, the net tax gap is estimated at $290 billion for Tax Year 2001). This paper explains the concept of the tax gap, discusses how it is estimated, and points out some limitations with the estimates.

  16. Small gaps between zeros of twisted L-functions

    CERN Document Server

    Conrey, J B; Soundararajan, K

    2012-01-01

    We use the asymptotic large sieve, developed by the authors, to prove that if the Generalized Riemann Hypothesis is true, then there exist many Dirichlet L-functions that have a pair of consecutive zeros closer together than 0.37 times their average spacing. More generally, we investigate zero spacings within the family of twists by Dirichlet characters of a fixed L-function and give precise bounds for small gaps which depend only on the degree of the L-function.

  17. Virtual MIMO Beamforming and Device Pairing Enabled by Device-to-Device Communications for Multidevice Networks

    Directory of Open Access Journals (Sweden)

    Yeonjin Jeong

    2017-01-01

    Full Text Available We consider a multidevice network with asymmetric antenna configurations which supports not only communications between an access point and devices but also device-to-device (D2D communications for the Internet of things. For the network, we propose the transmit and receive beamforming with the channel state information (CSI for virtual multiple-input multiple-output (MIMO enabled by D2D receive cooperation. We analyze the sum rate achieved by a device pair in the proposed method and identify the strategies to improve the sum rate of the device pair. We next present a distributed algorithm and its equivalent algorithm for device pairing to maximize the throughput of the multidevice network. Simulation results confirm the advantages of the transmit CSI and D2D cooperation as well as the validity of the distributive algorithm.

  18. Structural Basis of Cooperative Ligand Binding by the Glycine Riboswitch

    OpenAIRE

    Butler, Ethan B.; Xiong, Yong; Wang, Jimin; Strobel, Scott A.

    2011-01-01

    The glycine riboswitch regulates gene expression through the cooperative recognition of its amino acid ligand by a tandem pair of aptamers. A 3.6Å crystal structure of the tandem riboswitch from the glycine permease operon of Fusobacterium nucleatum reveals the glycine binding sites and an extensive network of interactions, largely mediated by asymmetric A-minor contacts, that serve to communicate ligand binding status between the aptamers. These interactions provide a structural basis for ho...

  19. Band-gap manipulations of monolayer graphene by phenyl radical adsorptions: a density functional theory study.

    Science.gov (United States)

    Huang, Lin; Sk, Mahasin Alam; Chen, Peng; Lim, Kok Hwa

    2014-08-25

    Phenyl radical (Ph˙) adsorption on monolayer graphene sheets is used to investigate the band-gap manipulation of graphene through density functional theory. Adsorption of a single Ph˙ on graphene breaks the aromatic π-bond and generates an unpaired electron, which is delocalized to the ortho or para position. Adsorption of a second radical at the ortho or para position saturates the radical by electron pairing and results in semiconducting graphene. Adsorption of a second radical at the ortho position (ortho-ortho pairing) is found to be more favorable than adsorption at the para position (ortho-para pairing), and the ortho-ortho pairing has stronger effects on band-gap opening compared with ortho-para pairing. Adsorption of even numbers of Ph˙ on graphene by ortho-ortho and ortho-para pairings, in general, increases the band gap. Our study shows promise of band-gap manipulation in monolayer graphene by Ph˙ adsorption, leading to potential wider applications of graphene. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Measuring the Gap

    Directory of Open Access Journals (Sweden)

    Xinshu She MD, MPH

    2016-02-01

    Full Text Available China is a large country where rapid development is accompanied by growing inequalities. How economic inequalities translate to health inequalities is unknown. Baseline health assessment is lacking among rural Chinese children. We aimed at assessing baseline student health of rural Chinese children and comparing them with those of urban children of similar ages. A cross-sectional study was conducted using the 2003 Global School-Based Student Health Survey among 100 students Grade 4 to 6 from rural Guizhou, China. Results were summarized and compared with public data from urban Beijing using multivariate logistic regression models. Rural children are more likely to not wash their hands before a meal (odds ratio [OR] = 5.71, P .05. Rural parents are more likely to not know their children’s whereabouts (OR = 1.81, P < .05. Rural children are more than 4 times likely to have serious injuries (OR = 4.64, P < .01 and to be bullied (OR = 4.01, P < .01. In conclusion, school-age rural Chinese children exhibit more health risk behaviors and fewer protective factors at baseline compared to their urban counterparts. Any intervention aimed at improving child health should take this distributive gap into consideration.

  1. Measuring the Gap

    Science.gov (United States)

    She, Xinshu; Zhao, Deqing; Scholnick, Jenna

    2016-01-01

    China is a large country where rapid development is accompanied by growing inequalities. How economic inequalities translate to health inequalities is unknown. Baseline health assessment is lacking among rural Chinese children. We aimed at assessing baseline student health of rural Chinese children and comparing them with those of urban children of similar ages. A cross-sectional study was conducted using the 2003 Global School-Based Student Health Survey among 100 students Grade 4 to 6 from rural Guizhou, China. Results were summarized and compared with public data from urban Beijing using multivariate logistic regression models. Rural children are more likely to not wash their hands before a meal (odds ratio [OR] = 5.71, P suicidal ideation in the past year (OR = 0.68, P > .05). Rural parents are more likely to not know their children’s whereabouts (OR = 1.81, P bullied (OR = 4.01, P < .01). In conclusion, school-age rural Chinese children exhibit more health risk behaviors and fewer protective factors at baseline compared to their urban counterparts. Any intervention aimed at improving child health should take this distributive gap into consideration. PMID:27335999

  2. Partner choice promotes cooperation: the two faces of testing with agent-based models.

    Science.gov (United States)

    Campennì, Marco; Schino, Gabriele

    2014-03-07

    Reciprocity is one of the most debated among the mechanisms that have been proposed to explain the evolution of cooperation. While a distinction can be made between two general processes that can underlie reciprocation (within-pair temporal relations between cooperative events, and partner choice based on benefits received), theoretical modelling has concentrated on the former, while the latter has been often neglected. We developed a set of agent-based models in which agents adopted a strategy of obligate cooperation and partner choice based on benefits received. Our models tested the ability of partner choice both to reproduce significant emergent features of cooperation in group living animals and to promote the evolution of cooperation. Populations formed by agents adopting a strategy of obligate cooperation and partner choice based on benefits received showed differentiated "social relationships" and a positive correlation between cooperation given and received, two common phenomena in animal cooperation. When selection across multiple generations was added to the model, agents adopting a strategy of partner choice based on benefits received outperformed selfish agents that did not cooperate. Our results suggest partner choice is a significant aspect of cooperation and provides a possible mechanism for its evolution.

  3. Cooperation Between Equals

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    2011 MARKS the 55th anniversary of the start of contemporary friendly relations between the People’s Republic of China and African countries. Chinese Vice Premier Hui Liangyu’s recent African trip gave another boost to the burgeoning China-Africa ties,said Chinese Vice Foreign Minister Zhai Jun.Hui visited five African countries - Mauritius, Zambia,the Democratic Republic of the Congo,Cameroon and Senegal -from January 6 to 19.Agriculture and trade were some of the most promising areas of cooperation between China and these countries,said Zhai in a recent interview with ChinAfrica.Excerpts follow:

  4. Cooperativity in beryllium bonds.

    Science.gov (United States)

    Alkorta, Ibon; Elguero, José; Yáñez, Manuel; Mó, Otilia

    2014-03-07

    A theoretical study of the beryllium bonded clusters of the (iminomethyl)beryllium hydride and (iminomethyl)beryllium fluoride [HC(BeX)=NH, X = H, F] molecules has been carried out at the B3LYP/6-311++G(3df,2p) level of theory. Linear and cyclic clusters have been characterized up to the decamer. The geometric, energetic, electronic and NMR properties of the clusters clearly indicate positive cooperativity. The evolution of the molecular properties, as the size of the cluster increases, is similar to those reported in polymers held together by hydrogen bonds.

  5. Particle migration and gap healing around trabecular metal implants

    DEFF Research Database (Denmark)

    Rahbek, O; Kold, S; Zippor, B;

    2005-01-01

    Bone on-growth and peri-implant migration of polyethylene particles were studied in an experimental setting using trabecular metal and solid metal implants. Cylindrical implants of trabecular tantalum metal and solid titanium alloy implants with a glass bead blasted surface were inserted either...... in an exact surgical fit or with a peri-implant gap into a canine knee joint. We used a randomised paired design. Polyethylene particles were injected into the knee joint. In both types of surgical fit we found that the trabecular metal implants had superior bone ongrowth in comparison with solid metal...... implants (exact fit: 23% vs. 7% [p=0.02], peri-implant gap: 13% vs. 0% [p=0.02]. The number of peri-implant polyethylene particles was significantly reduced around the trabecular metal implants with a peri-implant gap compared with solid implants....

  6. The Effects of Temperature Priming on Cooperation in the Iterated Prisoner's Dilemma

    Directory of Open Access Journals (Sweden)

    Simon Storey

    2013-01-01

    Full Text Available Based on initial research findings by Williams and Bargh (2008 and Kang, Williams, Clark, Gray and Bargh (2011 on the interaction between interpersonal and physical warmth, theoretical models such as cognitive scaffolding and the importance of evaluations of interpersonal warmth in trust-based decisions, this experiment investigated the effect of temperature priming on 30 pairs of British university students with hot and cold objects on frequency of cooperation in a game of iterated Prisoner's Dilemma. Participants were found to cooperate significantly more frequently when primed with hot objects than with cold objects, supporting the assertion that physical warmth sensation positively affects interpersonal trust evaluation. No support was found for the prediction that male-male pairs would cooperate less than female-female pairs. The implications of these findings to evolutionary and developmental theories of interpersonal warmth are discussed.

  7. The effects of temperature priming on cooperation in the iterated prisoner's dilemma.

    Science.gov (United States)

    Storey, Simon; Workman, Lance

    2013-01-25

    Based on initial research findings by Williams and Bargh (2008) and Kang, Williams, Clark, Gray and Bargh (2011) on the interaction between interpersonal and physical warmth, theoretical models such as cognitive scaffolding and the importance of evaluations of interpersonal warmth in trust-based decisions, this experiment investigated the effect of temperature priming on 30 pairs of British university students with hot and cold objects on frequency of cooperation in a game of iterated Prisoner's Dilemma. Participants were found to cooperate significantly more frequently when primed with hot objects than with cold objects, supporting the assertion that physical warmth sensation positively affects interpersonal trust evaluation. No support was found for the prediction that male-male pairs would cooperate less than female-female pairs. The implications of these findings to evolutionary and developmental theories of interpersonal warmth are discussed.

  8. The impact of size of cooperative group on achievement, social support, and self-esteem.

    Science.gov (United States)

    Bertucci, Andrea; Conte, Stella; Johnson, David W; Johnson, Roger T

    2010-01-01

    The effect of cooperative learning in pairs and groups of 4 and in individualistic learning were compared on achievement, social support, and self-esteem. Sixty-two Italian 7th-grade students with no previous experience with cooperative learning were assigned to conditions on a stratified random basis controlling for ability, gender, and self-esteem. Students participated in 1 instructional unit for 90 min for 6 instructional days during a period of about 6 weeks. The results indicate that cooperative learning in pairs and 4s promoted higher achievement and greater academic support from peers than did individualistic learning. Students working in pairs developed a higher level of social self-esteem than did students learning in the other conditions.

  9. An Outer Bound for the Memoryless Two-user Interference Channel with General Cooperation

    CERN Document Server

    Tuninetti, Daniela

    2012-01-01

    The interference channel models a wireless network where several source-destination pairs compete for the same resources. When nodes transmit simultaneously the destinations experience interference. This paper considers a 4-node network, where two nodes are sources and the other two are destinations. All nodes are full-duplex and cooperate to mitigate interference. A sum-rate outer bound is derived, which is shown to unify a number of previously derived outer bounds for special cases of cooperation. The approach is shown to extend to cooperative interference networks with more than two source-destination pairs and for any partial sum-rate. How the derived bound relates to similar bounds for channel models including cognitive nodes, i.e., nodes that have non-causal knowledge of the messages of some other node, is also discussed. Finally, the bound is evaluated for the Gaussian noise channel and used to compare different modes of cooperation.

  10. Skew Pairs of Idempotents in Transformation Semigroups

    Institute of Scientific and Technical Information of China (English)

    T. S. BLYTH; M. H. ALMEIDA SANTOS

    2006-01-01

    An ordered pair (e, f) of idempotents of a regular semigroup is called a skew pair if ef is not idempotent whereas fe is idempotent. We have shown previously that there are four distinct types of skew pairs of idempotents. Here we investigate the ubiquity of such skew pairs in full transformation semigroups.

  11. Influence of the isovector pairing effect on the nuclear statistical quantities

    Energy Technology Data Exchange (ETDEWEB)

    Belabbas, Mohamed [Faculte des Sciences et des Sciences de l Ingenieur, Universite Hassiba Ben Bouali, Chlef (Algeria); Ami, Ismahane [Institut des Sciences et de la Technologie, Universite Yahia Fares de Medea (Algeria); Laboratoire de Physique Theorique, Faculte de Physique, USTHB, Algier (Algeria); Benhamouda, Naziha [Laboratoire de Physique Theorique, Faculte de Physique, USTHB, Algier (Algeria); Fellah, Mohamed; Allal, Nassima-Hosni [Laboratoire de Physique Theorique, Faculte de Physique, USTHB, Algier (Algeria); Centre de Recherche Nucleaire d' Alger, COMENA, Algier (Algeria)

    2009-07-01

    Temperature-dependent isovector pairing gap equations have been recently established using a path integral approach. In the present work, the expressions of the main usual statistical properties, that is, the energy, the entropy and the heat capacity are established within the same model. These expressions generalize the Finite Temperature BCS (FTBCS) ones for the pairing between like-particles. Numerical calculations are carried out within the one-level model. The obtained results are compared to those of the usual FTBCS approach for the pairing between like-particles.

  12. Photon Attenuation and Pair Creation in Highly-Magnetized Pulsars

    CERN Document Server

    Baring, M G; Baring, Matthew G.; Harding, Alice K.

    1999-01-01

    Developments over the last couple of years have supported the interpretation that anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs) possess unusually high magnetic fields, and furthermore may represent a class or classes of neutron stars distinct from the population of conventional radio pulsars. We have recently suggested that such a dichotomization of the pulsar population may naturally arise due to the inherently different conditions in subcritical and supercritical magnetic fields. In this paper, we summarize, within the polar gap model, expectations for observable properties of highly magnetized pulsars, conventional or anomalous. This includes a discussion of the potential suppression of pair production and cascade generation in very strong fields by photon splitting and by threshold pair creation, which might explain radio quiescence in AXPs and SGRs. X-ray and hard gamma-ray spectral properties and trends are identified, with a view to establishing goals for future high energy experimenta...

  13. Approximating local observables on projected entangled pair states

    Science.gov (United States)

    Schwarz, M.; Buerschaper, O.; Eisert, J.

    2017-06-01

    Tensor network states are for good reasons believed to capture ground states of gapped local Hamiltonians arising in the condensed matter context, states which are in turn expected to satisfy an entanglement area law. However, the computational hardness of contracting projected entangled pair states in two- and higher-dimensional systems is often seen as a significant obstacle when devising higher-dimensional variants of the density-matrix renormalization group method. In this work, we show that for those projected entangled pair states that are expected to provide good approximations of such ground states of local Hamiltonians, one can compute local expectation values in quasipolynomial time. We therefore provide a complexity-theoretic justification of why state-of-the-art numerical tools work so well in practice. We finally turn to the computation of local expectation values on quantum computers, providing a meaningful application for a small-scale quantum computer.

  14. Semi-microscopic model of pairing in nuclei

    CERN Document Server

    Pankratov, S S; Baldo, M; Lombardo, U; Saperstein, E E

    2011-01-01

    A semi-microscopic model for nucleon pairing in nuclei is presented starting from the ab intio BCS gap equation with Argonne v18 force and the self-consistent Energy Density Functional Method basis characterized with the bare nucleon mass. The BCS theory is formulated in terms of the model space S0 with the effective pairing interaction calculated from the first principles in the subsidiary space S0. This effective interaction is supplemented with a small phenomenological addendum containing one phenomenological parameter universal for all medium and heavy atomic nuclei. We consider the latter as a phenomenological way to take into account both the many-body corrections to the BCS theory and the effective mass effects. For protons, the Coulomb interaction is introduced directly. Calculations made for several isotopic and isotonic chains of semi-magic nuclei confirm the validity of the model. The role of the self-consistent basis is stressed.

  15. GAP Analysis. Bulletin Number 11

    Science.gov (United States)

    2002-01-01

    in 2002 ( ESSB • Creation of a stewardship map is central to GAP’s analysis 6400) that authorizes a comprehensive review to identify the state’s method...governments and their consultants. "Washington State Law ESSB 6400 can be accessed at www.leg.wa.gov/pubfbillinfo/2001-02/Senate, January 10, 2003. Gap

  16. PhoneGap for enterprise

    CERN Document Server

    Shotts, Kerri

    2014-01-01

    This book is intended for developers who wish to use PhoneGap to develop useful, rich, secure mobile applications for their enterprise environment. The book assumes you have working knowledge of PhoneGap, HTML5, CSS3, and JavaScript, and a reasonable understanding of networking and n-tier architectures.

  17. Gap Structure and Gapless Structure in Fractional Quantum Hall Effect

    Directory of Open Access Journals (Sweden)

    Shosuke Sasaki

    2012-01-01

    Full Text Available Higher-order composite fermion states are correlated with many quasiparticles. The energy calculations are very complicated. We develop the theory of Tao and Thouless to explain them. The total Hamiltonian is (+, where includes Landau energies and classical Coulomb energies. We find the most uniform electron configuration in Landau states which has the minimum energy of . At =(2−1/(2, all the nearest electron pairs are forbidden to transfer to any empty states because of momentum conservation. Therefore, perturbation energies of the nearest electron pairs are zero in all order of perturbation. At =/(2−1, /(2+1, all the nearest electron (or hole pairs can transfer to all hole (or electron states. At =4/11, 4/13, 5/13, 5/17, 6/17, only the specific nearest hole pairs can transfer to all electron states. For example, the nearest-hole-pair energy at =4/11 is lower than the limiting energies from both sides (the left side =(4+1/(11+3 and the right side =(4−1/(11−3 for infinitely large . Thus, the nearest-hole-pair energy at specific is different from the limiting values from both sides. The property yields energy gap for the specific . Also gapless structure appears at other filling factors (e.g., at =1/2.

  18. The paradox of cooperation benefits.

    Science.gov (United States)

    Németh, A; Takács, K

    2010-05-21

    It seems obvious that as the benefits of cooperation increase, the share of cooperators in the population should also increase. It is well known that positive assortment between cooperative types, for instance in spatially structured populations, provide better conditions for the evolution of cooperation than complete mixing. This study demonstrates that, assuming positive assortment, under most conditions higher cooperation benefits also increase the share of cooperators. On the other hand, under a specified range of payoff values, when at least two payoff parameters are modified, the reverse is true. The conditions for this paradox are determined for two-person social dilemmas: the Prisoner's Dilemma, the Hawks and Doves game, and the Stag Hunt game, assuming global selection and positive assortment.

  19. Models in cooperative game theory

    CERN Document Server

    Branzei, Rodica; Tijs, Stef

    2008-01-01

    This book investigates models in cooperative game theory in which the players have the possibility to cooperate partially. In a crisp game the agents are either fully involved or not involved at all in cooperation with some other agents, while in a fuzzy game players are allowed to cooperate with infinite many different participation levels, varying from non-cooperation to full cooperation. A multi-choice game describes the intermediate case in which each player may have a fixed number of activity levels. Different set and one-point solution concepts for these games are presented. The properties of these solution concepts and their interrelations on several classes of crisp, fuzzy, and multi-choice games are studied. Applications of the investigated models to many economic situations are indicated as well. The second edition is highly enlarged and contains new results and additional sections in the different chapters as well as one new chapter.

  20. Pairing theory of striped superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Loder, Florian; Kampf, Arno P.; Kopp, Thilo; Graser, Siegfried [Center for Electronic Correlations and Magnetism, Institute of Physics, Augsburg (Germany)

    2011-07-01

    Striped high-T{sub c} superconductors such as La{sub 7/8}Ba{sub 1/8}CuO{sub 4} show a fascinating competition between spin and charge order on the one hand and superconductivity on the other. A theory for these systems therefore has to capture both the spin correlations in an antiferromagnet and the pair-correlation of a superconductor. For this purpose we have developed an effective Hartree-Fock theory by merging electron pairing with finite center-of-mass momentum and antiferromagnetism. We show that this theory reproduces the key experimental features such as the formation of the antiferromagnetic stripe patterns at 7/8 band filling or the quasi one-dimensional electronic structure observed by photoemission spectroscopy.

  1. Collisions of Vortex Filament Pairs

    Science.gov (United States)

    Banica, Valeria; Faou, Erwan; Miot, Evelyne

    2014-12-01

    We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

  2. Pairing in Luttinger Liquids and Quantum Hall States

    Science.gov (United States)

    Kane, Charles L.; Stern, Ady; Halperin, Bertrand I.

    2017-07-01

    We study spinless electrons in a single-channel quantum wire interacting through attractive interaction, and the quantum Hall states that may be constructed by an array of such wires. For a single wire, the electrons may form two phases, the Luttinger liquid and the strongly paired phase. The Luttinger liquid is gapless to one- and two-electron excitations, while the strongly paired state is gapped to the former and gapless to the latter. In contrast to the case in which the wire is proximity coupled to an external superconductor, for an isolated wire there is no separate phase of a topological, weakly paired superconductor. Rather, this phase is adiabatically connected to the Luttinger liquid phase. The properties of the one-dimensional topological superconductor emerge when the number of channels in the wire becomes large. The quantum Hall states that may be formed by an array of single-channel wires depend on the Landau-level filling factors. For odd-denominator fillings ν =1 /(2 n +1 ), wires at the Luttinger phase form Laughlin states, while wires in the strongly paired phase form a bosonic fractional quantum Hall state of strongly bound pairs at a filling of 1 /(8 n +4 ). The transition between the two is of the universality class of Ising transitions in three dimensions. For even-denominator fractions ν =1 /2 n , the two single-wire phases translate into four quantum Hall states. Two of those states are bosonic fractional quantum Hall states of weakly and strongly bound pairs of electrons. The other two are non-Abelian quantum Hall states, which originate from coupling wires close to their critical point. One of these non-Abelian states is the Moore-Read state. The transitions between all of these states are of the universality class of Majorana transitions. We point out some of the properties that characterize the different phases and the phase transitions.

  3. Anisotropic superconducting gap and elongated vortices with Caroli-De Gennes-Matricon states in the new superconductor Ta4Pd3Te16.

    Science.gov (United States)

    Du, Zengyi; Fang, Delong; Wang, Zhenyu; Li, Yufeng; Du, Guan; Yang, Huan; Zhu, Xiyu; Wen, Hai-Hu

    2015-01-01

    The superconducting state is formed by the condensation of a large number of Cooper pairs. The normal state electronic properties can give significant influence on the superconducting state. For usual type-II superconductors, the vortices are cylinder like with a round cross-section. For many two dimensional superconductors, such as Cuprates, albeit the in-plane anisotropy, the vortices generally have a round shape. In this paper we report results based on the scanning tunnelling microscopy/spectroscopy measurements on a newly discovered superconductor Ta4Pd3Te16. The chain-like conducting channels of PdTe2 in Ta4Pd3Te16 make a significant anisotropy of the in-plane Fermi velocity. We suggest at least one anisotropic superconducting gap with gap minima or possible node exists in this multiband system. In addition, elongated vortices are observed with an anisotropy of ξ||b/ξ&bottom⊥b ≈ 2.5. Clear Caroli-de Gennes-Matricon states are also observed within the vortex cores. Our results will initiate the study on the elongated vortices and superconducting mechanism in the new superconductor Ta4Pd3Te16.

  4. Septin pairs, a complex choreography.

    Science.gov (United States)

    Ewers, Helge

    2011-06-13

    Septins form a filamentous collar at the mother-bud neck in budding yeast. In cytokinesis, this collar splits into two rings and the septin complexes undergo a dramatic reorientation. Using fluorescence polarization microscopy, DeMay et al. (2011. J. Cell Biol. doi:10.1083/jcb.201012143) now demonstrate that septin complexes assemble as paired filaments in vivo and reveal new insights into septin organization during cytokinesis.

  5. Mir Cooperative Solar Array

    Science.gov (United States)

    Skor, Mike; Hoffman, Dave J.

    1997-01-01

    The Mir Cooperative Solar Array (MCSA), produced jointly by the United States and Russia, was deployed on the Mir Russian space station on May 25, 1996. The MCSA is a photovoltaic electrical power system that can generate up to 6 kW. The power from the MCSA is needed to extend Mir's lifetime and to support experiments conducted there by visiting U.S. astronauts. The MCSA was brought to Mir via the Space Shuttle Atlantis on the STS-74 mission, launched November 12, 1995. This cooperative venture combined the best technology of both countries: the United States provided high-efficiency, lightweight photovoltaic panel modules, whereas Russia provided the array structure and deployment mechanism. Technology developed in the Space Station Freedom Program, and now being used in the International Space Station, was used to develop MCSA's photovoltaic panel. Performance data obtained from MCSA operation on Mir will help engineers better understand the performance of the photovoltaic panel modules in orbit. This information will be used to more accurately predict the performance of the International Space Station solar arrays. Managed by the NASA Lewis Research Center for NASA's International Space Station Program Office in Houston, Texas, the MCSA Project was completed on time and under budget despite a very aggressive schedule.

  6. Components of the Belief Gap

    Directory of Open Access Journals (Sweden)

    Cecilie Gaziano

    2014-01-01

    Full Text Available Knowledge gap research focuses on education as an indicator of socioeconomic status (SES. Belief gap research centers on ideology as potentially more powerful than education in comparing sociopolitical groups with scientifically established knowledge and groups with opposing beliefs accepted on faith. This study examined the relationship between education and ideology to understand belief gaps better. The study used 2008 American National Election Study (ANES data to compare conservatives, moderates, and liberals by education on religiosity, child rearing values, opinionation, need for cognition, orientation toward politics, and mass media access and use. Although liberals tended to be more educated than conservatives overall, better-educated conservatives had the highest household incomes and were a much larger group. No known knowledge gap studies have reported results on one group characterized by high education and an opposing group distinguished by a different indicator of SES. Reformulations of the belief gap hypothesis are offered.

  7. Paired Stimulation to Promote Lasting Augmentation of Corticospinal Circuits

    Directory of Open Access Journals (Sweden)

    Noam Y. Harel

    2016-01-01

    Full Text Available After injury, electrical stimulation of the nervous system can augment plasticity of spared or latent circuits through focal modulation. Pairing stimulation of two parts of a spared circuit can target modulation more specifically to the intended circuit. We discuss 3 kinds of paired stimulation in the context of the corticospinal system, because of its importance in clinical neurorehabilitation. The first uses principles of Hebbian plasticity: by altering the stimulation timing of presynaptic neurons and their postsynaptic targets, synapse function can be modulated up or down. The second form uses synchronized presynaptic inputs onto a common synaptic target. We dub this a “convergent” mechanism, because stimuli have to converge on a common target with coordinated timing. The third form induces focal modulation by tonic excitation of one region (e.g., the spinal cord during phasic stimulation of another (e.g., motor cortex. Additionally, endogenous neural activity may be paired with exogenous electrical stimulation. This review addresses what is known about paired stimulation of the corticospinal system of both humans and animal models, emphasizes how it qualitatively differs from single-site stimulation, and discusses the gaps in knowledge that must be addressed to maximize its use and efficacy in neurorehabilitation.

  8. Morse theory and stable pairs

    CERN Document Server

    Wentworth, Richard A

    2010-01-01

    We study the Morse theory of the Yang-Mills-Higgs functional on the space of pairs $(A,\\Phi)$, where $A$ is a unitary connection on a rank 2 hermitian vector bundle over a compact Riemann surface, and $\\Phi$ is a holomorphic section of $(E, d_A")$. We prove that a certain explicitly defined substratification of the Morse stratification is perfect in the sense of $\\G$-equivariant cohomology, where $\\G$ denotes the unitary gauge group. As a consequence, Kirwan surjectivity holds for pairs. It also follows that the twist embedding into higher degree induces a surjection on equivariant cohomology. This may be interpreted as a rank 2 version of the analogous statement for symmetric products of Riemann surfaces. Finally, we compute the $\\G$-equivariant Poincar\\'e polynomial of the space of $\\tau$-semistable pairs. In particular, we recover an earlier result of Thaddeus. The analysis provides an interpretation of the Thaddeus flips in terms of a variation of Morse functions.

  9. Mediators of homologous DNA pairing.

    Science.gov (United States)

    Zelensky, Alex; Kanaar, Roland; Wyman, Claire

    2014-10-09

    Homologous DNA pairing and strand exchange are at the core of homologous recombination. These reactions are promoted by a DNA-strand-exchange protein assembled into a nucleoprotein filament comprising the DNA-pairing protein, ATP, and single-stranded DNA. The catalytic activity of this molecular machine depends on control of its dynamic instability by accessory factors. Here we discuss proteins known as recombination mediators that facilitate formation and functional activation of the DNA-strand-exchange protein filament. Although the basics of homologous pairing and DNA-strand exchange are highly conserved in evolution, differences in mediator function are required to cope with differences in how single-stranded DNA is packaged by the single-stranded DNA-binding protein in different species, and the biochemical details of how the different DNA-strand-exchange proteins nucleate and extend into a nucleoprotein filament. The set of (potential) mediator proteins has apparently expanded greatly in evolution, raising interesting questions about the need for additional control and coordination of homologous recombination in more complex organisms. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  10. The Professionalization of Intelligence Cooperation

    DEFF Research Database (Denmark)

    Svendsen, Adam David Morgan

    "Providing an in-depth insight into the subject of intelligence cooperation (officially known as liason), this book explores the complexities of this process. Towards facilitating a general understanding of the professionalization of intelligence cooperation, Svendsen's analysis includes risk...... management and encourages the realisation of greater resilience. Svendsen discusses the controversial, mixed and uneven characterisations of the process of the professionalization of intelligence cooperation and argues for a degree of 'fashioning method out of mayhem' through greater operational...

  11. The Professionalization of Intelligence Cooperation

    DEFF Research Database (Denmark)

    Svendsen, Adam David Morgan

    "Providing an in-depth insight into the subject of intelligence cooperation (officially known as liason), this book explores the complexities of this process. Towards facilitating a general understanding of the professionalization of intelligence cooperation, Svendsen's analysis includes risk...... management and encourages the realisation of greater resilience. Svendsen discusses the controversial, mixed and uneven characterisations of the process of the professionalization of intelligence cooperation and argues for a degree of 'fashioning method out of mayhem' through greater operational...

  12. Cooperative Directors: Perspective and Leadership

    OpenAIRE

    Adrian, John L., Jr.; Kiser, Stephen L.

    2000-01-01

    Cooperative directors’ perceptions of their roles, knowledge, and implementation of cooperative principles, business decision making, financial analysis, cooperative law, and division of responsibility with management were analyzed using data from forty-eight agricultural and thirty-one rural electric directors. Directors performed well in these areas with the best performance being related to decision-making scenarios. Self-assessments and performance for capabilities/situational items wer...

  13. Teleworking through cooperation

    Directory of Open Access Journals (Sweden)

    Dario Minervini

    2006-07-01

    scheme is strictly connected to new technologies and cooperation is an important dimension of teleworking. In our study, cooperation is found performed both in social relations between employers and employees and in institutionalized relations between managers and unions. Although the two forms of cooperation, here called “social trustee cooperation” and “institutional cooperation”, are often thought as prerequisites of “best practices” of new working arrangements, our case studies demonstrate that cooperation has not always arisen that make possible to implement practices of teleworking. By focusing on cooperative relations, the results of different case studies in industry and in the service sector are discussed, thus intending to contribute to the development of sociological debate on telework.

  14. Cooperation and between-group competition

    OpenAIRE

    Hausken, Kjell

    2000-01-01

    Introducing competition between groups may induce cooperation to emerge in defection games despite considerable cost of cooperation. If the groups can confine themselves to a cooperative sector, either by providing incentives to raise the cooperation level in one group, or by providing disincentives so that the cooperation level in the other group gets lowered to match that of the first, maximum degrees of cooperation can be obtained. The cooperative sector broadens as the degrees of cooperat...

  15. International Grants and Cooperative Agreements

    Science.gov (United States)

    EPA provides grants and enters into cooperative agreements that support protecting human health and the environment while advancing U.S. national interests through international environmental collaboration.

  16. Mechanisms for similarity based cooperation

    Science.gov (United States)

    Traulsen, A.

    2008-06-01

    Cooperation based on similarity has been discussed since Richard Dawkins introduced the term “green beard” effect. In these models, individuals cooperate based on an aribtrary signal (or tag) such as the famous green beard. Here, two different models for such tag based cooperation are analysed. As neutral drift is important in both models, a finite population framework is applied. The first model, which we term “cooperative tags” considers a situation in which groups of cooperators are formed by some joint signal. Defectors adopting the signal and exploiting the group can lead to a breakdown of cooperation. In this case, conditions are derived under which the average abundance of the more cooperative strategy exceeds 50%. The second model considers a situation in which individuals start defecting towards others that are not similar to them. This situation is termed “defective tags”. It is shown that in this case, individuals using tags to cooperate exclusively with their own kind dominate over unconditional cooperators.

  17. Success and failure of firms' innovation co-operations: The role of intermediaries and reciprocity

    DEFF Research Database (Denmark)

    Cantner, U.; Meder, A.; Wolf, T.

    2011-01-01

    attempts to fill this gap by investigating the possible presence of two problems in co-operation: the lack of intermediation and of reciprocity. Based on data gathered for firms in two German regions and one French region, we find that the success of co-operation projects depends on the perceived...... importance, rather than on the perceived quality, of intermediate actors. Hence, the major problem for intermediating suitable partners is more related to communication than it is a programmatic issue. Trust and reciprocity in co-operation between firms is found to be relevant ex-post in the sense of being...

  18. Bit Loading Algorithms for Cooperative OFDM Systems

    Directory of Open Access Journals (Sweden)

    Bo Gui

    2007-12-01

    Full Text Available We investigate the resource allocation problem for an OFDM cooperative network with a single source-destination pair and multiple relays. Assuming knowledge of the instantaneous channel gains for all links in the entire network, we propose several bit and power allocation schemes aiming at minimizing the total transmission power under a target rate constraint. First, an optimal and efficient bit loading algorithm is proposed when the relay node uses the same subchannel to relay the information transmitted by the source node. To further improve the performance gain, subchannel permutation, in which the subchannels are reallocated at relay nodes, is considered. An optimal subchannel permutation algorithm is first proposed and then an efficient suboptimal algorithm is considered to achieve a better complexity-performance tradeoff. A distributed bit loading algorithm is also proposed for ad hoc networks. Simulation results show that significant performance gains can be achieved by the proposed bit loading algorithms, especially when subchannel permutation is employed.

  19. Bit Loading Algorithms for Cooperative OFDM Systems

    Directory of Open Access Journals (Sweden)

    Gui Bo

    2008-01-01

    Full Text Available Abstract We investigate the resource allocation problem for an OFDM cooperative network with a single source-destination pair and multiple relays. Assuming knowledge of the instantaneous channel gains for all links in the entire network, we propose several bit and power allocation schemes aiming at minimizing the total transmission power under a target rate constraint. First, an optimal and efficient bit loading algorithm is proposed when the relay node uses the same subchannel to relay the information transmitted by the source node. To further improve the performance gain, subchannel permutation, in which the subchannels are reallocated at relay nodes, is considered. An optimal subchannel permutation algorithm is first proposed and then an efficient suboptimal algorithm is considered to achieve a better complexity-performance tradeoff. A distributed bit loading algorithm is also proposed for ad hoc networks. Simulation results show that significant performance gains can be achieved by the proposed bit loading algorithms, especially when subchannel permutation is employed.

  20. Boron/nitrogen pairs Co-doping in metallic carbon nanotubes: a first-principle study

    Institute of Scientific and Technical Information of China (English)

    Ouyang Fang-Ping; Peng Sheng-Lin; Chen Ling-Na; Sun Shu-Yuan; Xu Hui

    2011-01-01

    By using the first-principles calculations, the electronic structure and quantum transport properties of metallic carbon nanotubes with B/N pairs co-doping have been investigated. It is shown that the total energies of metallic carbon nanotubes are sensitive to the doping sites of the B/N pairs. The energy gaps of the doped metallic carbon nanotubes decrease with decreasing the concentration of the B/N pair not only along the tube axis but also around the tube. Moreover, the I-V characteristics and transmissions of the doped tubes are studied. Our results reveal that the conducting ability of the doped tube decreases with increasing the concentrations of the B/N pairs due to symmetry breaking of the system. This fact opens a new way to modulate band structures of metallic carbon nanotubes by doping B/N pair with suitable concentration and the novel characteristics are potentially useful in future applications.