bluuebunny/crossref_metadata_2025 huggingface dataset:
Periodic steady state solution of distribution networks via sweeping iterations
Authors: Morales Eric , Ramirez Abner
Published: June 2013

This study describes an enhanced hybrid method for calculating the periodic steady state of radial and weakly meshed distribution networks. The forward/backward sweeping technique has been taken here as basis to compute the network's equilibrium, accounting that non‐linear elements and electronic devices are included. On one hand, a modified harmonic domain (MHD), based on the discrete Fourier transform (DFT), has been used to account for harmonics and interharmonics simultaneously, involving only matrix/vector operations. On the other hand, non‐linear elements and electronic devices are handled in the time domain and included in the sweeping solution scheme by interfacing MHD and time domain through DFT operations. The proposed hybrid sweeping‐based technique and a Newton‐based method are compared here through a network example.
Self-diffusion of wet particles in rotating drums
Authors: Liu P. Y. , Yang R. Y. , Yu A. B.
Published: June 2013

Axial mixing of wet particles in rotating drums was investigated by the discrete element method with the capillary force explicitly considered. Different flow regimes were observed by varying the surface tension of liquid and keeping other conditions unchanged. The analysis of the concentration and mean square displacement of particles indicated that the axial motion of wet particles was a diffusive process characterised by Fick's law. Particle diffusivity decreased with increasing inter-particle cohesion and drum filling level but increased with increasing drum rotation speed. Two competing mechanisms were proposed to explain these effects. A theoretical model based on the relation between local diffusivity and shear rate was developed to predict particle diffusivity as a function of drum operation conditions. It was also observed that despite the high inhomogeneity of particle flow in rotating drums, the mean diffusivity of flow exhibited a strong correlation with granular temperature, defined as the mean square fluctuating velocity of particles.
Mesoscale simulation of semiflexible chains. I. Endpoint distribution and chain dynamics
Authors: Groot Robert D.
Published: June 2013

The endpoint distribution and dynamics of semiflexible fibers are studied by numerical simulation. A brief overview is given over the analytical theory of flexible and semiflexible polymers. In particular, a closed expression is given for the relaxation spectrum of wormlike chains, which determines polymer diffusion and rheology. Next a simulation model for wormlike chains with full hydrodynamic interaction is described, and relations for the bending and torsion modulus are given. Two methods are introduced to include torsion stiffness into the model. The model is validated by simulating single chains in a heat bath, and comparing the endpoint distribution of the chains with established Monte Carlo results. It is concluded that torsion stiffness leads to a slightly shorter effective persistence length for a given bending stiffness. To further validate the simulation model, polymer diffusion is studied for fixed persistence length and varying polymer length N. The diffusion constant shows crossover from Rouse (D ∝ N−1) to reptation behaviour (D ∝ N−2). The terminal relaxation time obtained from the monomer displacement is consistent with the theory of wormlike chains. The probability for chain crossing has also been studied. This probability is so low that it does not influence the present results.
Mesoscale simulation of semiflexible chains. II. Evolution dynamics and stability of fiber bundle networks
Authors: Groot Robert D.
Published: June 2013

Network formation of associative semiflexible fibers and mixtures of fibers and colloidal particles is simulated for the Johnson-Kendall-Roberts model of elastic contacts, and a phase diagram in terms of particle elasticity and surface energy is presented. When fibers self-assemble, they form a network for sufficiently large fiber-solvent surface energy. If the surface energy is above the value where single particles crystallize, the adhesion forces drive diffusion-limited aggregation. Two mechanisms contribute to coarsening: non-associated chains joining existing bundles, and fiber bundles merging. Coarsening stops when the length of the network connections is roughly the persistence length, independent of surface energy. If the surface energy is below the value where single particles crystallize, a network can still be formed but at a much slower (reaction limited) rate. Loose (liquid-like) assemblies between chains form when they happen to run more-or-less parallel. These assemblies grow by diffusion and aggregation and form a loose network, which sets in micro-phase separation, i.e., syneresis. Only when the clusters crystallize, the coarsening process stops. In this case, the length of the network connections is larger than the persistence length of a single chain, and depends on the value of the surface energy. All networks of semiflexible homopolymers in this study show syneresis. Mixtures of fibers and colloid particles also form fiber bundle networks, but by choosing the colloid volume fraction sufficiently low, swelling gels are obtained. Applications of this model are in biological systems where fibers self-assemble into cell walls and bone tissue.
Birth and death processes and quantum spin chains
Authors: Grünbaum F. Alberto , Vinet Luc , Zhedanov Alexei
Published: June 2013

This paper underscores the intimate connection between the quantum walks generated by certain semi-infinite spin chain Hamiltonians and classical birth and death processes. It is observed that transition amplitudes between single excitation states of the spin chains have an expression in terms of orthogonal polynomials which is analogous to the Karlin-McGregor representation formula of the transition probability functions for classes of birth and death processes. As an application, we present a characterization of spin systems for which the probability to return to the point of origin at some time is 1 or almost 1.
The surprising metastability of TeH2+
Authors: de Oliveira-Filho Antonio G. S. , Ornellas Fernando R.
Published: June 2013

A high-level ab initio investigation of a manifold of electronic states of the diatomic dication TeH2+ is presented. Potential energy curves for both Λ + S and relativistic (Ω) states are constructed not only making evident the metastability of this system, but also the large energy splitting due to spin-orbit interactions. This effect is also very significant in the region close to the crossing of the 2Π and 4Σ− states, where avoided crossings between the Ω states have a relatively large impact on the height of the energy barriers. In contrast to TeH, with only two bound states (X1 2Π3/2 and X2 2Π1/2) below about 25 000 cm−1, in the case of TeH2+ a much richer energy profile is obtained indicating various possibilities of electronic transitions. Guided by the results of this study, the experimental characterization of these states is now a challenge to spectroscopists. Since close to the equilibrium region the double positive charge is centered on the tellurium atom, the binding in this system can be rationalized as a simple covalent bond between the pz and s orbitals of Te2+ and H, respectively. As the internuclear distance increases, the electron affinity of Te2+ overcomes that of H+ and the system dissociates into two singly charged fragments. A simulation of the double ionization spectra complements the characterization of the electronic states, and results of a mass spectrometric investigation corroborates the predicted transient existence of this metastable species.
Assessment of various natural orbitals as the basis of large active space density-matrix renormalization group calculations
Authors: Ma Yingjin , Ma Haibo
Published: June 2013

It is well-known that not only the orbital ordering but also the choice of the orbitals itself as the basis may significantly influence the computational efficiency of density-matrix renormalization group (DMRG) calculations. In this study, for assessing the efficiency of using various natural orbitals (NOs) as the DMRG basis, we performed benchmark DMRG calculations with different bases, which included the NOs obtained by various traditional electron correlation methods, as well as NOs acquired from preliminary moderate DMRG calculations (e.g., preserved states less than 500). The tested systems included N2, transition metal Cr2 systems, as well as 1D hydrogen polyradical chain systems under equilibrium and dissociation conditions and 2D hydrogen aggregates. The results indicate that a good compromise between the requirement for low computational costs of acquiring NOs and the demand for high efficiency of NOs as the basis of DMRG calculations may be very dependent on the studied systems’ diverse electron correlation characteristics and the size of the active space. It is also shown that a DMRG-complete active space configuration interaction (DMRG-CASCI) calculation in a basis of carefully chosen NOs can provide a less expensive alternative to the standard DMRG-complete active space self-consistent field (DMRG-CASSCF) calculation and avoid the convergence difficulties of orbital optimization for large active spaces. The effect of different NO ordering schemes on DMRG-CASCI calculations is also discussed.
Disconnected glass-glass transitions and swallowtail bifurcations in microscopic spin models with facilitated dynamics
Authors: Sellitto Mauro
Published: June 2013

It has been recently established that heterogeneous bootstrap percolation and related dynamic facilitation models exhibit a complex hierarchy of continuous and discontinuous transitions depending on lattice connectivity and kinetic constraints. Here the range of the previously observed phase diagram topologies and higher-order singularities is extended to disconnected glass-glass transitions and to cusp and swallowtail bifurcations (which can be generic and degenerate). The phase diagram and the order parameter for two different types of spin mixtures are analytically determined and an experimental realization of the new predictions emerging in our approach is suggested.
CdTe grown under Cd/Te excess at very low temperatures for solar cells
Authors: Heisler C. , Brückner M. , Lind F. , Kraft C. , Reislöhner U. , Ronning C. , Wesch W.
Published: June 2013

A low-temperature physical vapour deposition method for CdTe absorber layers was developed in this study and the influence of the substrate temperature during absorber growth is discussed in terms of the phase diagram of CdTe. The composition of CdTe layers grown at substrate temperatures between 45 and 300 °C with 3 different evaporation source arrangements producing either a stoichiometric, a Te-rich or a Cd-rich material supply was investigated by energy-dispersive X-ray spectroscopy. Absorber layers which were produced below a substrate temperature of 190 °C with the standard evaporation method using stoichiometric CdTe as source material show a significant Te excess which leads to non working solar cells. The application of Cd-rich material supply yields a stoichiometric growth of the absorber layers and good solar cell characteristics for substrate temperatures as low as 100 °C.
Enhancement of thermal conductivity of silver nanofluid synthesized by a one-step method with the effect of polyvinylpyrrolidone on thermal behavior
Authors: Salehi J. M. , Heyhat M. M. , Rajabpour A.
Published: June 2013

A one-step chemical method has been developed for the preparation of stable, non-agglomerated silver nanofluids. Silver nanofluid is prepared by using silver nitrate as a source for silver nanoparticles, distilled water as a base fluid, and sodium borohydride and hydrazine as reducing agents by means of conventional heating using polyvinylpyrrolidone (PVP) as surfactant. This is an in situ, one-step method that seems to be valuable with high yield of product with less time consumption. The characterization of the nanofluid is done by particle size analyzer, X-ray diffraction topography, UV-visible absorption spectroscopy, and transmission electron microscopy followed by the study of thermal conductivity of nanofluid by the transient hot wire method. The results show that Ag-water nanofluids with low concentration of nanoparticles, i.e., below 1000 ppm, have noticeably higher thermal conductivities than the water base fluid without Ag. Moreover, the amount of PVP in silver nanofluid can have a significant effect on magnitude and behavior of the thermal conductivity enhancement.
Near-field characterization of chemical vapor deposition graphene in the microwave regime
Authors: Katsounaros Anestis , Cole Matthew T. , Tuncer Hatice M. , Milne William I. , Hao Yang
Published: June 2013

Near-field measurements were performed at X-band frequencies for graphene on copper microstrip transmission lines. An improvement in radiation of 0.88 dB at 10.2 GHz is exhibited from the monolayer graphene antenna which has dc sheet resistivity of 985 Ω/sq. Emission characteristics were validated via ab initio simulations and compared to empirical findings of geometrically comparable copper patches. This study contributes to the current knowledge of the electronic properties of graphene.
Mirror force induced wave dispersion in Alfvén waves
Authors: Damiano P. A. , Johnson J. R.
Published: June 2013

Recent hybrid MHD-kinetic electron simulations of global scale standing shear Alfvén waves along the Earth's closed dipolar magnetic field lines show that the upward parallel current region within these waves saturates and broadens perpendicular to the ambient magnetic field and that this broadening increases with the electron temperature. Using resistive MHD simulations, with a parallel Ohm's law derived from the linear Knight relation (which expresses the current-voltage relationship along an auroral field line), we explore the nature of this broadening in the context of the increased perpendicular Poynting flux resulting from the increased parallel electric field associated with mirror force effects. This increased Poynting flux facilitates wave energy dispersion across field lines which in-turn allows for electron acceleration to carry the field aligned current on adjacent field lines. This mirror force driven dispersion can dominate over that associated with electron inertial effects for global scale waves.
Observation of whispering gallery modes in microtube-microspheres system
Authors: Li Hanyang , Hao Sue , Qiang Liangsheng , Li Jin , Zhang Yundong
Published: June 2013

We proposed that a fluorescent microsphere with diameter of 6 μm was manipulated into a microtube with inner diameter of 6.2 μm. The whispering gallery modes (WGMs) of fluorescence resonance were observed by 532 nm laser pumping the microspheres-mircotube system. Another microsphere with the same diameter was manipulated into the microtube and mode splitting in the system of two spheres in contact in the mircotube was demonstrated. We also discussed relationship between WGMs peak intensity and the excitation power. The scheme will bring more insight into the applications of WGMs for biomedical diagnostics and microfluidics.
Communication: Two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): Simultaneous planar imaging and multiplex spectroscopy in a single laser shot
Authors: Bohlin Alexis , Kliewer Christopher J.
Published: June 2013

Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15 000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm2.
Upconversion properties and dynamics study in Tm3+ and Yb3+ codoped CaSc2O4 oxide material
Authors: Li Jing , Zhang Jiahua , Hao Zhendong , Zhang Xia , Zhao Jihong , Luo Yongshi
Published: June 2013

The upconversion properties of Tm3+ and Yb3+ codoped CaSc2O4 phosphor excited at 980 nm are reported. The blue emission of Tm3+:1G4 → 3H6, red emission of Tm3+:1G4 → 3F4, near-infrared emissions of Tm3+:3H4 → 3H6 (800 nm) and 3F4 → 3H6 (1600 nm) are observed when excited Yb3+:2F5/2 level. The spectral properties of Yb3+:2F5/2 and Tm3+:3F4, 3H4, 1G4 levels are described in detail as a function of Yb3+ and Tm3+ concentrations. By the trends of intensity ratios of Tm3+:3F4 to Yb3+:2F5/2 and Tm3+:1G4 to 3H4 with the doped concentrations, upconversion dynamics is analyzed in Tm3+ and Yb3+ codoped CaSc2O4 material. The concentration dependent lifetimes of Yb3+:2F5/2 and Tm3+:1G4, 3H4 levels measured prove the existence of the efficient Yb3+ → Tm3+ energy transfer and followed Tm3+ → Yb3+ back-energy transfer processes, respectively. The energy transfer efficiency is up to 70% before concentration quenching occurrence. The back-energy transfer process is evidenced by the presence of the Yb3+:2F5/2 → 2F7/2 in the emission spectrum excited Tm3+:1G4 level at 466 nm. The detailed spectroscopic study conduces to understand the upconversion dynamics process in Tm3+ and Yb3+ codoped excellent CaSc2O4 oxide material.
Femtosecond laser diagnostics of the built-in electric field across the p+-Si/SiO2 interface and its ultrafast shielding
Authors: Neethling P. H. , Rohwer E. G. , Stafast H.
Published: June 2013

Ultrafast shielding of the built-in electric field E0 across the p+-Si/SiO2 interface of boron doped Si upon near infrared femtosecond (fs) laser pulse irradiation (73 ± 5 fs, 35 GW/cm2≤ Ipeak(ω) ≤ 115 GW/cm2) is shown to be dominated by electron-hole (e-h) pairs generated via two-photon absorption (TPA), whereas contributions from one-photon absorption (OPA) appear negligible. E0 shows up in the instantaneous signal I(2ω)(t≈0)≈I(2ω)(E0) of the Electric Field Induced Second Harmonic (EFISH). Its power law is derived from the linear log I(2ω)(E0) vs. log (Ipeak(ω))n plots of six fs laser wavelengths 741.2 nm ≤ λ ≤ 801.0 nm for the first time. These reveal 1.2 ≤ n(λ) ≤ 2.1 with the minimum at λ = 752.4 nm (2hν = 3.3 eV) related to resonantly enhanced TPA. Shielding of E0 by e-h pairs from OPA cannot be detected by EFISH in the same fs laser pulse as their generation requires relatively slow electron-phonon coupling.
Dynamics simulations for engineering macromolecular interactions
Authors: Robinson-Mosher Avi , Shinar Tamar , Silver Pamela A. , Way Jeffrey
Published: June 2013

The predictable engineering of well-behaved transcriptional circuits is a central goal of synthetic biology. The artificial attachment of promoters to transcription factor genes usually results in noisy or chaotic behaviors, and such systems are unlikely to be useful in practical applications. Natural transcriptional regulation relies extensively on protein-protein interactions to insure tightly controlled behavior, but such tight control has been elusive in engineered systems. To help engineer protein-protein interactions, we have developed a molecular dynamics simulation framework that simplifies features of proteins moving by constrained Brownian motion, with the goal of performing long simulations. The behavior of a simulated protein system is determined by summation of forces that include a Brownian force, a drag force, excluded volume constraints, relative position constraints, and binding constraints that relate to experimentally determined on-rates and off-rates for chosen protein elements in a system. Proteins are abstracted as spheres. Binding surfaces are defined radially within a protein. Peptide linkers are abstracted as small protein-like spheres with rigid connections. To address whether our framework could generate useful predictions, we simulated the behavior of an engineered fusion protein consisting of two 20 000 Da proteins attached by flexible glycine/serine-type linkers. The two protein elements remained closely associated, as if constrained by a random walk in three dimensions of the peptide linker, as opposed to showing a distribution of distances expected if movement were dominated by Brownian motion of the protein domains only. We also simulated the behavior of fluorescent proteins tethered by a linker of varying length, compared the predicted Förster resonance energy transfer with previous experimental observations, and obtained a good correspondence. Finally, we simulated the binding behavior of a fusion of two ligands that could simultaneously bind to distinct cell-surface receptors, and explored the landscape of linker lengths and stiffnesses that could enhance receptor binding of one ligand when the other ligand has already bound to its receptor, thus, addressing potential mechanisms for improving targeted signal transduction proteins. These specific results have implications for the design of targeted fusion proteins and artificial transcription factors involving fusion of natural domains. More broadly, the simulation framework described here could be extended to include more detailed system features such as non-spherical protein shapes and electrostatics, without requiring detailed, computationally expensive specifications. This framework should be useful in predicting behavior of engineered protein systems including binding and dissociation reactions.
Experimental observation of transition from chaotic bursting to chaotic spiking in a neural pacemaker
Authors: Gu Huaguang
Published: June 2013

The transition from chaotic bursting to chaotic spiking has been simulated and analyzed in theoretical neuronal models. In the present study, we report experimental observations in a neural pacemaker of a transition from chaotic bursting to chaotic spiking within a bifurcation scenario from period-1 bursting to period-1 spiking. This was induced by adjusting extracellular calcium or potassium concentrations. The bifurcation scenario began from period-doubling bifurcations or period-adding sequences of bursting pattern. This chaotic bursting is characterized by alternations between multiple continuous spikes and a long duration of quiescence, whereas chaotic spiking is comprised of fast, continuous spikes without periods of quiescence. Chaotic bursting changed to chaotic spiking as long interspike intervals (ISIs) of quiescence disappeared within bursting patterns, drastically decreasing both ISIs and the magnitude of the chaotic attractors. Deterministic structures of the chaotic bursting and spiking patterns are also identified by a short-term prediction. The experimental observations, which agree with published findings in theoretical neuronal models, demonstrate the existence and reveal the dynamics of a neuronal transition from chaotic bursting to chaotic spiking in the nervous system.
Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite
Authors: Lu Haibao , Min Huang Wei
Published: June 2013

The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.
Labyrinth-type domain structure of heteroepitaxial SrMnO2.5 film
Authors: Kobayashi Shunsuke , Ikuhara Yuichi , Yamamoto Takahisa
Published: June 2013

SrMnO2.5 films grown on SrTiO3 and LSAT substrates were prepared and oxygen vacancies in the films were directly confirmed by annular bright-field imaging in a scanning transmission electron microscope. The SrMnO2.5 films show a unique maze like pattern of domains, i.e., a labyrinth-type domain structure, that arises from relaxation of strain induced by lattice mismatches. The behavior of the domain widths is explained by the geometrical relationship for estimating of the average distance of misfit dislocations. We present useful principles for controlling the domain structures with a view to potential practical applications.
Mott-type MgxZn1-xO-based visible-blind ultraviolet photodetectors with active anti-reflection layer
Authors: Xie X. H. , Zhang Z. Z. , Li B. H. , Wang S. P. , Jiang M. M. , Shan C. X. , Zhao D. X. , Chen H. Y. , Shen D. Z.
Published: June 2013

We report on a vertical geometry Mott-type visible (VIS)-blind Ultraviolet (UV) photodetector which was fabricated based on wurzite MgZnO (W-MgZnO) with a cubic MgZnO (C-MgZnO) anti-reflection layer. The C-MgZnO layer plays two roles in the detector, not only the conventional optical part but also electrical part. Photon-generated holes were restricted due to valence band offset. More “hot” electrons injected over a reduced Mott potential barrier at the metal-semiconductor interface, resulting in additional current contributing to photoresponse. This dual-function structure is a highly compact and wavelength-resonant UV detector, with a spectral response high-gain and fast.
Giant dielectric constant in CaCu3Ti4O12 nanoceramics
Authors: Ahmad Mohamad M.
Published: June 2013

Nanoceramics of CaCu3Ti4O12 (CCTO) were synthesized by mechanosynthesis and spark plasma sintering with grain size of 150–200 nm. Giant dielectric constant properties are observed in the CCTO nanoceramics due to internal barrier layer capacitance (IBLC) effects. Impedance spectroscopy data suggest that the presence of resistive grain boundaries in addition to resistive domain boundaries is the origin of the IBLCs in CCTO nanoceramics.
Highly efficient -1st-order reflection in Littrow mounted dielectric double-groove grating
Authors: Ito Kota , Iizuka Hideo
Published: June 2013

We show that in a silicon double-groove grating with two different groove widths per period attached on top of a semi-infinite SiO2 substrate, almost 100% reflectivity is achieved for the -1st-order reflection with an incident angle of 60° in the Littrow mounting condition. The modal analysis reveals that modes propagating in the upward and downward directions have nearly the same amplitudes at resonance. They are added constructively for the -1st-order reflection and destructively for the 0th-order reflection and the -1st-order and 0th-order transmission. The asymmetric structure with a dielectric material poses a unique feature as a four port device.
Evaluating the No Cold Calling Zones in Peterborough, England: Application of a Novel Statistical Method for Evaluating Neighbourhood Policing Policies
Authors: Li Guangquan , Haining Robert , Richardson Sylvia , Best Nicky
Published: June 2013

Some police forces in the UK institute ‘No Cold Calling’ (NCC) zones to reduce cold callings (unsolicited visits to sell products or services), which are often associated with rogue trading and distraction burglary. This paper evaluates the NCC-targeted areas chosen in 2005–06 in Peterborough and reports whether they experienced a measurable impact on their burglary rates in the period up to 2008. Time-series data for burglary at the census output area level are analysed using a Bayesian hierarchical modelling approach to address issues of data sparsity and lack of randomised allocation of areas to treatment groups that are often encountered in small-area quantitative policy evaluation. To ensure internal validity, we employ the interrupted time-series quasi-experimental design embedded within a matched case-control framework. Results reveal a positive impact of NCC zones on reducing burglary rates in the targeted areas compared with the control areas.
Intermediaries and Capability Building in ‘Emerging’ Clusters
Authors: Clarke Ian , Ramirez Matias
Published: June 2013

Increasing attention has begun to focus on the important role that organisations undertaking intermediary functions can play in supporting emerging clusters of small producers. In contrast to most studies of intermediaries that focus on governance and filling information gaps, in this paper we examine how the organisational skills of intermediaries evolve as firms in the cluster assume a broader range of practices. Through a purpose-built typology and a detailed case study, the argument is made not only that intermediaries act to facilitate the diffusion of knowledge but also that their scope of activities, extending into coordinating joint actions and new investment initiatives, places them at the centre of the network of organisations. This growing influence of intermediaries has implications for producer firms, especially in aspects such as inclusion of smaller producers and network formation.
Adaptation Effects to Attractiveness of Face Photographs and Art Portraits are Domain-Specific
Authors: Hayn-Leichsenring Gregor U. , Kloth Nadine , Schweinberger Stefan R. , Redies Christoph
Published: June 2013

We studied the neural coding of facial attractiveness by investigating effects of adaptation to attractive and unattractive human faces on the perceived attractiveness of veridical human face pictures (Experiment 1) and art portraits (Experiment 2). Experiment 1 revealed a clear pattern of contrastive aftereffects. Relative to a pre-adaptation baseline, the perceived attractiveness of faces was increased after adaptation to unattractive faces, and was decreased after adaptation to attractive faces. Experiment 2 revealed similar aftereffects when art portraits rather than face photographs were used as adaptors and test stimuli, suggesting that effects of adaptation to attractiveness are not restricted to facial photographs. Additionally, we found similar aftereffects in art portraits for beauty, another aesthetic feature that, unlike attractiveness, relates to the properties of the image (rather than to the face displayed). Importantly, Experiment 3 showed that aftereffects were abolished when adaptors were art portraits and face photographs were test stimuli. These results suggest that adaptation to facial attractiveness elicits aftereffects in the perception of subsequently presented faces, for both face photographs and art portraits, and that these effects do not cross image domains.
Pd(II) and Pt(II) Coordination Chemistry with Hybrid Pyridine-Pyrazole Ligands: from 3D-Frameworks Structures in Molecular Complexes
Authors: Guerrero Miguel , Pérez José A. , Calvet Teresa , Font-Bardía Mercè , Pons Josefina
Published: June 2013

In this paper we studied the reaction of ligands 2-[5-phenyl-1-(3,6,9-trioxodecane)-1H-pyrazol-3-yl]pyridine (L1) and 3,5-bis(2-pyridyl)-1-(3,6,9-trioxodecane)-1H-pyrazole (L2) with [MCl2(CH3CN)2] (M = Pd(ii), Pt(ii)), to obtain monomeric complexes [MCl2(L)] (M = Pd(ii): L = L1 (1), L = L2 (2); M = Pt(ii): L = L1 (3), L = L2 (4)). Additionally, the reaction of [Pd(CH3COO)2] with L1 (5) and L2 (6) was also studied pointing out dimeric structures with bridged acetates between the Pd(ii) atoms. All complexes were characterised by elemental analyses, conductivity measurements, infrared spectroscopy (IR), 1H, 13C{1H}, and 195Pt{1H} NMR spectroscopies, and electrospray ionisation mass spectrometry (MS-ESI(+)). The crystal structure of complex [PtCl2(L1)] (3) was determined by X-ray diffraction methods; it consists of a mononuclear complex where L1 acts as a bidentate chelate ligand. Moreover, we also studied the extended structure observing that the ether, present in the alkyl chain of the ligand, chlorine, and platinum moieties play a fundamental role in the final disposition of the supramolecular structure. All these results show how the design of an appropriate hybrid ligand can strongly influence the structural control of the molecular packing.
Polyester synthesis genes associated with stress resistance are involved in an insect–bacterium symbiosis
Authors: Kim Jiyeun Kate , Won Yeo Jin , Nikoh Naruo , Nakayama Hiroshi , Han Sang Heum , Kikuchi Yoshitomo , Rhee Young Ha , Park Ha Young , Kwon Jeong Yun , Kurokawa Kenji , Dohmae Naoshi , Fukatsu Takema , Lee Bok Luel
Published: June 2013

Significance

This study reports a previously unrecognized involvement of polyhydroxyalkanoate (PHA), known as a bacterial endocellular storage polymer, in an insect–bacterium symbiosis. Many bacteria in the environment accumulate PHA granules within their cells, which provide resistance to nutritional depletion and other environmental stresses. Here we demonstrate that synthesis and accumulation of PHA in the symbiont cells are required for normal symbiotic association with, and, consequently, positive fitness effects for the host insect. The requirement of PHA for symbiosis suggests that, contrary to the general expectation, the within-host environment may be, at least in some aspects, stressful for the symbiotic bacteria.
Detection of an intermediary, protonated water cluster in photosynthetic oxygen evolution
Authors: Polander Brandon C. , Barry Bridgette A.
Published: June 2013

In photosynthesis, photosystem II evolves oxygen from water by the accumulation of photooxidizing equivalents at the oxygen-evolving complex (OEC). The OEC is a Mn
4
CaO
5
cluster, and its sequentially oxidized states are termed the S
n
states. The dark-stable state is S
1
, and oxygen is released during the transition from S
3
to S
0
. In this study, a laser flash induces the S
1
to S
2
transition, which corresponds to the oxidation of Mn(III) to Mn(IV). A broad infrared band, at 2,880 cm
−1
, is produced during this transition. Experiments using ammonia and
2
H
2
O assign this band to a cationic cluster of internal water molecules, termed “W
5
+
.” Observation of the W
5
+
band is dependent on the presence of calcium, and flash dependence is observed. These data provide evidence that manganese oxidation during the S
1
to S
2
transition results in a coupled proton transfer to a substrate-containing, internal water cluster in the OEC hydrogen-bonded network.
Neutron diffraction observations of interstitial protons in dense ice
Authors: Guthrie Malcolm , Boehler Reinhard , Tulk Christopher A. , Molaison Jamie J. , dos Santos António M. , Li Kuo , Hemley Russell J.
Published: June 2013

The motif of distinct H
2
O molecules in H-bonded networks is believed to persist up to the densest molecular phase of ice. At even higher pressures, where the molecule dissociates, it is generally assumed that the proton remains localized within these same networks. We report neutron-diffraction measurements on D
2
O that reveal the location of the D atoms directly up to 52 GPa, a pressure regime not previously accessible to this technique. The data show the onset of a structural change at ∼13 GPa and cannot be described by the conventional network structure of ice VII above ∼26 GPa. Our measurements are consistent with substantial deuteron density in the octahedral, interstitial voids of the oxygen lattice. The observation of this “interstitial” ice VII form provides a framework for understanding the evolution of hydrogen bonding in ice that contrasts with the conventional picture. It may also be a precursor for the superionic phase reported at even higher pressure with important consequences for our understanding of dense matter and planetary interiors.
People are more likely to be insincere when they are more likely to accidentally tell the truth
Authors: Leblois Sylvie , Bonnefon Jean-François
Published: June 2013

Although people lie often, and mostly for self-serving reasons, they do not lie as much as they could. The “fudge factor” hypothesis suggests that one reason for people not to lie is that they do not wish to self-identify as liars. Accordingly, self-serving lies should be more likely when they are less obvious to the liars themselves. Here we show that the likelihood of self-serving lies increases with the probability of accidentally telling the truth. Players in our game could transmit sincere or insincere recommendations to their competitors. In line with the fudge factor hypothesis, players lied when their beliefs were based on flimsy evidence and did not lie when their beliefs were based on solid evidence. This is the first demonstration of a new moral hypocrisy paradox: People are more likely to be insincere when they are more likely to accidentally tell the truth.
Does Tonal Information Affect the Early Stages of Visual-Word Processing in Thai?
Authors: Winskel Heather , Perea Manuel
Published: June 2013

Thai offers a unique opportunity to investigate the role of lexical tone processing during visual-word recognition, as tone is explicitly expressed in its script. In order to investigate the contribution of tone at the orthographic/phonological level during the early stages of word processing in Thai, we conducted a masked priming experiment—using both lexical decision and word naming tasks. For a given target word (e.g., ห้อง/hᴐ:ŋ2/, room), five priming conditions were created: (a) identity (e.g., ห้อง/hᴐ:ŋ2/), (b) same initial consonant, but with a different tone marker (e.g., ห่อง/hᴐ:ŋ1/), (c) different initial consonant, but with the same tone marker (e.g., ศ้อง/sᴐ:ŋ2/), (d) orthographic control (different initial consonant, different tone marker; e.g., ศ่อง/sᴐ:ŋ1/), and (e) same tone homophony, but with a different initial consonant and different tone marker (e.g., ธ่อง/thᴐ:ŋ2/). Results of the critical comparisons revealed that segmental information (i.e., consonantal information) appears to be more important than tone information (i.e., tone marker) in the early stages of visual-word processing in alphabetic, tonal languages like Thai. Thus, these findings may help constrain models of visual-word recognition and reading in tonal languages.
The question concerning metaphysics: a Schellingian intervention in analytical psychology
Authors: McGrath Sean
Published: June 2013

Schelling is the least understood of the major German philosophers. His work has a clearly demonstrable influence on the late nineteenth-century psychologies of the unconscious that were a decisive influence on both Freud and Jung. Where the mature Freudian metapsychology is a systematic effort to de-Romanticize the unconscious, purging it of the characteristic Schellingian themes of transcendence, teleology, and theology, Jung goes in the opposite direction: toward a psychology of transcendence, with cosmological and religious implications. This makes Schellingian psychology a natural ally to analytical psychology. But to exploit this hitherto neglected resource, Jungians must overcome Jung's antipathy for metaphysics.
Saturnian mean motion resonances in meteoroid streams
Authors: Sekhar A. , Asher D. J.
Published: June 2013

Many previous works have shown the relevance and dynamics of Jovian mean motion resonances (MMR) in various meteoroid streams. These resonant swarms are known to have produced spectacular meteor displays in the past. In this work, we investigate whether any MMR due to Saturn are feasible, and subsequently check whether such effects are strong enough to trap meteoroids so as to cause enhanced meteor phenomena on Earth. Extensive numerical simulations are done on two major meteoroid streams, which are known to exhibit exterior Jovian resonances. The roles of the 1:6 and 5:14 Jovian MMR have already been studied in the Orionids and Leonids, respectively. Now we find strong evidence of 1:3 and 8:9 Saturnian MMR in Orionids and Leonids, respectively. The presence of compact dust trails in real space due to these two Saturnian resonances is confirmed from our calculations.
An observation of solar active region expansion into the heliosphere
Authors: Morgan H.
Published: June 2013

According to current models, solar closed-field active regions are isolated from contributing directly to the solar wind except through small- or large-scale magnetic reconnection, including coronal mass ejections. Here we show the first direct evidence of active regions contributing directly to the solar wind by a steady-state, quiescent expansion. Advanced image processing of coronagraph data reveals a large system of nested closed-field magnetic structures expanding and accelerating to heights of at least 14 R⊙ within a helmet streamer above a large active region. The system persists for several days, and must therefore be an important contribution to the slow solar wind.
Latin Historiography
Authors: Ring Abram
Published: June 2013

Latin historiography can mean how history was written in Latin in ancient times and how modern scholars interpret histories written in Latin. Here the works cited cover Latin historiography from its origins in Cato the Elder (2nd century bce) and the early Roman annalists to the historians of the Late Empire (5th century ce). The biggest controversy in this field comes out of differing interpretations of the relationship between rhetoric and history. Rhetoric was undeniably ever present in Latin historiography, but many modern historians of the ancient world would prefer to see rhetoric as mere ornamentation that we can carefully remove in order to find the truth buried underneath. Literary scholars of historiography, on the other hand, argue that some ancient thinkers thought of history as a branch of rhetoric or at least as inextricable from rhetoric, and that we must remember that rhetorical inventio was basically a process of fictional composition, so sometimes ancient histories may be more fictional than historical in the modern sense. Both sides will agree that ancient histories are much different from modern historical writing, and that the reader must always be aware of rhetoric and other cultural influences in order to get the most out of the texts. History was a fluid genre in the ancient world and had close connections with prose genres such as geography and ethnography as well as poetic genres such as tragedy and epic—these connections help to illustrate just how different Roman histories are from modern historical writing.
Plato's Timaeus
Authors: Johansen Thomas
Published: June 2013

The Timaeus presents Plato’s theory of the cosmos. It exercised a strong influence on other ancient philosophers, including Aristotle, Galen, and the Stoics, not to mention later Platonists such as Plutarch, Proclus, and Plotinus. Its doctrine of a creator god inspired Early Christian thought, while in the Middle Ages it was one of the few Platonic works being read in the West. In modern times, after a period of relative neglect, it is now enjoying a resurgence of scholarly interest. The cosmology of the Timaeus explains the perceptible world as the creation of a benevolent god, the demiurge or “craftsman.” To make it as good as possible, the god fashioned the cosmos as an image of an eternal paradigm, specifically that of a complete living being. As a living being itself, the world has a rational soul and a body. Its immaterial soul rotates according to mathematical ratios, thereby causing the regular revolutions of the planets and the stars. Its body is composed of basic bodies—earth, air, water, and fire, each of which is built up geometrically from triangles in different configurations. Timaeus, the main speaker, introduces a “receptacle,” also dubbed “space” (chôra), to explain how the basic bodies come about and move. He explains the various sensible qualities through the motions of the basic bodies. Human beings are endowed with a rational soul, which when embodied acquires irrational parts. The demiurge’s assistants have, however, constructed these parts and the human body to help us survive and to develop our rationality. From this point of view, Timaeus describes the body’s various structures in detail. The aim of human life is to maximize our rationality through imitation of the world’s soul. Men who fail to do so are reincarnated as women or lower animals. For more on Plato, see the separate Oxford Bibliographies article Plato.
Athenian Agora
Authors: Camp John
Published: June 2013

A large open square, surrounded on all four sides by public buildings, the Agora of Athens was in all respects the center of town. From the beginning the square was used for a variety of activities: marketplace, elections, dramatic performances, athletic contests, religious processions, and military drill. The excavation of buildings, monuments, and small objects has illustrated the important role it played in all aspects of civic life. The senate chamber (bouleuterion), public office buildings (Royal Stoa, South Stoa I), and archives (metroon) have all been excavated. The law courts are represented by the discovery of bronze ballots and a water clock used to time speeches. The use of the area as a marketplace is suggested by the numerous shops and workrooms where potters, cobblers, bronzeworkers, and sculptors made and sold their wares. Long stoas, or colonnades, provided shaded walkways for those wishing to meet friends to discuss business, politics, or philosophy, and statues and commemorative monuments reminded citizens of former triumphs. A library and concert hall met cultural needs, and numerous shrines and temples received regular worship in the area. Thus administrative, political, judicial, commercial, social, cultural, and religious activities all found a place here together in the heart of ancient Athens from the 6th century bce until the 6th century ce.
Research Ethics
Authors: Anastas Jeane W.
Published: June 2013

As research activity in social work has increased, so has attention to ethics in research. Research ethics guide the relationship between researcher(s) and research participant(s), researchers’ relationships to the organizations and communities in which their studies are conducted, and relationships among researchers and scholars. They also safeguard the integrity of knowledge development and dissemination activities, serving society by ensuring that science generates findings that can be trusted. Social work research adheres to the ethical principles and practices that guide the responsible conduct of research (RCR) in the biomedical and social sciences. However, social work research must also reflect the professional and ethical aims of all social work activities.