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Theory of meaning

Mark Hadfield, Michael Jopling
The paper argues that case study will need to play an increasingly important role in the evaluation of leadership development programmes as both formal and substantive theories of leadership place greater emphasis upon the role played by organizational context on leaders ability to bring about change. Prolonged engagement within a case study provides researchers with opportunities to capture the dynamics between leaders and their organisational contexts. However, adopting a case study approach is no substitute for inadequate theorization of the link between leadership approaches and leadership effects...
January 8, 2018: Evaluation and Program Planning
J Segarra-Martí, M Garavelli, F Aquilante
We present an extrapolation scheme for the correlation energy in many-body theory that requires only a relatively small fraction of the orbitals spanning the virtual space but recovers nearly the whole dynamic correlation energy, independently of the single- or multi-reference nature of the problem. Applications to both ground-state chemistry and photochemistry are discussed that clearly show how such an extrapolation scheme can be used to overcome the scaling walls in ab initio quantum chemistry arising from the sheer number of molecular orbitals needed for very accurate calculations...
January 21, 2018: Journal of Chemical Physics
Manikandan Krishnan, Rukshana Pervin, Kalai Selvan Ganesan, Kannan Murugesan, Govindaraj Lingannan, Akshay Kumar Verma, Parasharam M Shirage, Arumugam Sonachalam
The impact of hydrostatic pressure (P) up to 1 GPa on T c , J c and the nature of the pinning mechanism in FexNbSe2 single crystals have been investigated within the framework of the collective theory. We found that the pressure can induce a transition from the regime where pinning is controlled by spatial variation in the critical transition temperature (δT c ) to the regime controlled by spatial variation in the mean free path (δℓ). Furthermore, T c and low field J c are slightly induced, although the J c drops more rapidly at high fields than at ambient P...
January 19, 2018: Scientific Reports
Amelia J Hessheimer, Marina Vendrell, Javier Muñoz, Ángel Ruíz, Alba Díaz, Luís Flores Sigüenza, Jorge Rodríguez Lanzilotta, Eduardo Delgado Oliver, Jose Fuster, Miquel Navasa, Juan Carlos García-Valdecasas, Pilar Taurá, Constantino Fondevila
BACKGROUND: Ischemic type biliary lesions arise most frequently after DCD liver transplantation and result in high morbidity and graft loss. Many DCD grafts are discarded out of fear for this complication. In theory, microvascular thrombi deposited during donor warm ischemia might be implicated in ITBL pathogenesis. Herein, we aim to evaluate the effects of the administration of either heparin or the fibrinolytic drug TPA as means to improve DCD liver graft quality and potentially avoid ITBL...
January 19, 2018: Liver Transplantation
Nicolas Turenne
Rumour is an old social phenomenon used in politics and other public spaces. It has been studied for only hundred years by sociologists and psychologists by qualitative means. Social media platforms open new opportunities to improve quantitative analyses. We scanned all scientific literature to find relevant features. We made a quantitative screening of some specific rumours (in French and in English). Firstly, we identified some sources of information to find them. Secondly, we compiled different reference, rumouring and event datasets...
2018: PloS One
Liqing Li, Xiancheng Ma, Ruofei Chen, Chunhao Wang, Mingming Lu
Nitrogen-doped porous carbon (ZC) is prepared by modification with ammonia for increasing the specific surface area and surface polarity after carbonization of zeolite imidazole framework-8 (ZIF-8). The structure and properties of these ZCs were characterized by Transmission electron microscopy, X-ray diffraction, N₂ sorption, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Through static adsorption tests of these carbons, the sample obtained at 600 °C was selected as an excellent adsorbent, which exhibited an excellent acetone capacity of 417...
January 19, 2018: Materials
Davide Lazzeri
Sandro Botticelli was one of the most esteemed painters and draughtsmen among Renaissance artists. Under the patronage of the De' Medici family, he was active in Florence during the flourishing of the Renaissance trend towards the reclamation of lost medical and anatomical knowledge of ancient times through the dissection of corpses. Combining the typical attributes of the elegant courtly style with hallmarks derived from the investigation and analysis of classical templates, he left us immortal masterpieces, the excellence of which incomprehensibly waned and was rediscovered only in the 1890s...
January 16, 2018: Acta Bio-medica: Atenei Parmensis
Jorge I Martínez-Araya, Daniel Glossman-Mitnik
Ten functionals were used to assess their capability to compute a local reactivity descriptor coming from the Conceptual Density Functional Theory on a group of iron-based organometallic compounds that have been synthesized by Zohuri, G.H. et al. in 2010; these compounds bear the following substituent groups: H-, O2N- and CH3O- at the para position of the pyridine ring and their catalytic activities were experimentally measured by these authors. The present work involved a theoretical analysis applied on the aforementioned iron-based compounds thus leading to suggest a new 2,6-bis(imino)pyridine catalyst based on iron(II) bearing a fluorine atom whose possible catalytic activity is suggested to be near the catalytic activity of the complex bearing a hydrogen atom as a substituent group by means of the so called local hyper-softness (LHS) thus opening a chance to estimate a possible value of catalytic activity for a new catalyst that has not been synthesized yet without simulating the entire process of ethylene polymerization...
January 18, 2018: Journal of Molecular Modeling
Jonathan Barés, Dengming Wang, Dong Wang, Thibault Bertrand, Corey S O'Hern, Robert P Behringer
We present the experimental and numerical studies of a two-dimensional sheared amorphous material composed of bidisperse photoelastic disks. We analyze the statistics of avalanches during shear including the local and global fluctuations in energy and changes in particle positions and orientations. We find scale-free distributions for these global and local avalanches denoted by power laws whose cutoffs vary with interparticle friction and packing fraction. Different exponents are found for these power laws depending on the quantity from which variations are extracted...
November 2017: Physical Review. E
Francisco Vega Reyes, Antonio Lasanta, Andrés Santos, Vicente Garzó
The dynamical properties of a tracer or impurity particle immersed in a host gas of inelastic and rough hard spheres in the homogeneous cooling state is studied. Specifically, the breakdown of energy equipartition as characterized by the tracer/host ratios of translational and rotational temperatures is analyzed by exploring a wide spectrum of values of the control parameters of the system (masses, moments of inertia, sizes, and coefficients of restitution). Three complementary approaches are considered. On the theoretical side, the Boltzmann and Boltzmann-Lorentz equations (both assuming the molecular chaos ansatz) are solved by means of a multitemperature Maxwellian approximation for the velocity distribution functions...
November 2017: Physical Review. E
Anna Yu Solovyova, Ekaterina A Elfimova, Alexey O Ivanov, Philip J Camp
The effects of particle-size polydispersity on the magnetostatic properties of concentrated ferrofluids are studied using theory and computer simulation. The second-order modified mean-field (MMF2) theory of Ivanov and Kuznetsova [Phys. Rev. E 64, 041405 (2001)1063-651X10.1103/PhysRevE.64.041405] has been extended by calculating additional terms of higher order in the dipolar coupling constant in the expansions of the initial magnetic susceptibility and the magnetization curve. The theoretical predictions have been tested rigorously against results from Monte Carlo simulations of model monodisperse, bidisperse, and highly polydisperse ferrofluids...
November 2017: Physical Review. E
Mihail Mintchev, Luca Santoni, Paul Sorba
The quantum fluctuations of the entropy production for fermionic systems in the Landauer-Büttiker nonequilibrium steady state are investigated. The probability distribution, governing these fluctuations, is explicitly derived by means of quantum field theory methods and analyzed in the zero frequency limit. It turns out that microscopic processes with positive, vanishing and negative entropy production occur in the system with nonvanishing probability. In spite of this fact, we show that all odd moments (in particular, the mean value of the entropy production) of the above distribution are non-negative...
November 2017: Physical Review. E
Kenta Ishibashi, Rina Kanamoto
The classical self-oscillations can collapse merely due to their mutual couplings. We investigate this oscillation collapse in quantum van der Pol oscillators. For a pair of quantum oscillators, the steady-state mean phonon number is shown to be lower than in the corresponding classical model with a Gaussian white noise that mimics quantum noise. We further show within the mean-field theory that a number of globally coupled oscillators undergo a transition from the synchronized periodic motion to the collective oscillation collapse...
November 2017: Physical Review. E
Igor Goychuk, Vasyl O Kharchenko, Ralf Metzler
Logarithmic or Sinai-type subdiffusion is usually associated with random force disorder and nonstationary potential fluctuations whose root-mean-squared amplitude grows with distance. We show here that extremely persistent, macroscopic logarithmic diffusion also universally emerges at sufficiently low temperatures in stationary Gaussian random potentials with spatially decaying correlations, known to exist in a broad range of physical systems. Combining results from extensive simulations with a scaling approach we elucidate the physical mechanism of this unusual subdiffusion...
November 2017: Physical Review. E
J Cheraghalizadeh, M N Najafi, H Dashti-Naserabadi, H Mohammadzadeh
The self-organized criticality on the random fractal networks has many motivations, like the movement pattern of fluid in the porous media. In addition to the randomness, introducing correlation between the neighboring portions of the porous media has some nontrivial effects. In this paper, we consider the Ising-like interactions between the active sites as the simplest method to bring correlations in the porous media, and we investigate the statistics of the BTW model in it. These correlations are controlled by the artificial "temperature" T and the sign of the Ising coupling...
November 2017: Physical Review. E
Shahar Amitai, Antonio Bertei, Raphael Blumenfeld
Solid-oxide fuel cells produce electric current from energy released by a spontaneous electrochemical reaction. The efficiency of these devices depends crucially on the microstructure of their electrodes and in particular on the three-phase boundary (TPB) length, along which the energy-producing reaction occurs. We present a systematic maximization of the TPB length as a function of four readily controllable microstructural parameters, for any given mean hydraulic radius, which is a conventional measure of the permeability to gas flow...
November 2017: Physical Review. E
Scott D Baalrud, Jérôme Daligault
The manner in which transport properties vary over the entire parameter-space of coupling and magnetization strength is explored. Four regimes are identified based on the relative size of the gyroradius compared to other fundamental length scales: the collision mean free path, Debye length, distance of closest approach, and interparticle spacing. Molecular dynamics simulations of self-diffusion and temperature anisotropy relaxation spanning the parameter space are found to agree well with the predicted boundaries...
October 2017: Physical Review. E
Rodrigo Freitas, Timofey Frolov, Mark Asta
Molecular dynamics (MD) simulations are employed to investigate the capillary fluctuations of steps on the surface of a model metal system. The fluctuation spectrum, characterized by the wave number (k) dependence of the mean squared capillary-wave amplitudes and associated relaxation times, is calculated for 〈110〉 and 〈112〉 steps on the {111} surface of elemental copper near the melting temperature of the classical potential model considered. Step stiffnesses are derived from the MD results, yielding values from the largest system sizes of (37±1)meV/A[over ˚] for the different line orientations, implying that the stiffness is isotropic within the statistical precision of the calculations...
October 2017: Physical Review. E
Daniel Stopper, Roland Roth
Using classical density functional theory, we investigate systems exhibiting interactions where a short-range anisotropic attractive force competes with a long-range spherically symmetric repulsive force. The former is modelled within Wertheim's first-order perturbation theory for patchy particles, and the repulsive part is assumed to be a Yukawa potential which is taken into account via a mean-field approximation. From previous studies of systems with spherically symmetric competing interactions, it is well known that such systems can exhibit stable bulk cluster phases (microphase separation) provided that the repulsion is sufficiently weak compared to the attraction...
October 2017: Physical Review. E
W Rozmus, A Brantov, C Fortmann-Grote, V Yu Bychenkov, S Glenzer
We present a theory of electrostatic fluctuations in two-component plasmas where electrons and ions are described by Maxwellian distribution functions at unequal temperatures. Based on the exact solution of the Landau kinetic equation, that includes electron-electron, electron-ion, and ion-ion collision integrals, the dynamic form factor, S(k[over ⃗],ω), is derived for weakly coupled plasmas. The collective plasma responses at ion-acoustic, Langmuir, and entropy mode resonances are described for arbitrary wave numbers and frequencies in the entire range of plasma collisionality...
October 2017: Physical Review. E
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