bluuebunny/crossref_metadata_2025 huggingface dataset:
Dopant-induced bandgap shift in Al-doped ZnO thin films prepared by spray pyrolysis
Authors: Hung-Chun Lai Henry , Basheer Tahseen , Kuznetsov Vladimir L. , Egdell Russell G. , Jacobs Robert M. J. , Pepper Michael , Edwards Peter P.
Published: October 2012

A series of 1 at. % Al-doped ZnO (AZO) films were deposited onto glass substrates by a spray pyrolysis technique. We find that the observed blue shift in the optical bandgap of 1% AZO films is dominated by the Burstein Moss effect. The Fermi level for an 807 nm thick AZO film rose by some 0.16 eV with respect to the edge of the conduction band. By controlling the film thickness, all AZO films exhibit the same lattice strain values. The influence of strain-induced bandgap shift was excluded by selecting films with nearly the same level of bandgap volume-deformation potentials, and the differences in out-plain strain and in-plain stress remained effectively constant.
Resonance splitting effect through magnetic superlattices in graphene
Authors: Lu Wei-Tao , Li Wen , Wang Yong-Long , Ye Cheng-Zhi , Jiang Hua
Published: October 2012

Using the transfer-matrix formalism, the resonance splitting effect of Dirac electrons through two types of magnetic superlattices in graphene is studied theoretically. The numerical results show that the transmission presents (n − 1)-fold resonance splitting for the both magnetic superlattices with n-barrier, similar to Schrödinger electrons in semiconductor superlattices. It is believed that the Dirac electrons possess a general (n − 1)-fold splitting rule for n-barrier magnetic superlattices, of which the corresponding vector potential is periodic field. The magnetic superlattices with strong magnetic field can be used as a very efficient wave-vector filter for Dirac electrons. The splitting feature of the transmission probability also reflects in the conductance and shot noise. These properties should be useful for the design of graphene-based electronic devices.
The source of holes in p-type InxGa1−xN films
Authors: Zvanut M. E. , Willoughby W. R. , Koleske D. D.
Published: October 2012

The origin of holes in Mg-doped InxGa1−xN films is investigated using electron paramagnetic resonance (EPR) spectroscopy. Unlike in Mg-doped GaN, the number of Mg-related acceptors in films with x between 0.021 and 0.112 decreases as the hole density increases. The EPR results indicate that the previously suggested models involving isolated acceptors or band formation cannot adequately explain hole production in InGaN. Rather, additional features such as In-induced passivating centers must be introduced.
Atomic structure and energy spectrum of Ga(As,P)/GaP heterostructures
Authors: Abramkin D. S. , Putyato M. A. , Budennyy S. A. , Gutakovskii A. K. , Semyagin B. R. , Preobrazhenskii V. V. , Kolomys O. F. , Strelchuk V. V. , Shamirzaev T. S.
Published: October 2012

The atomic structure and energy spectrum of Ga(As,P)/GaP heterostructures were studied. It was shown that the deposition of GaAs of the same nominal thickness leads to the formation of pseudomorphic GaAs/GaP quantum wells (QW), fully relaxed GaAs/GaP self-assembled quantum dots (SAQDs), or pseudomorphic GaAsP/GaP SAQDs depending on the growth temperature. We demonstrate that the atomic structure of Ga(As,P)/GaP heterostructures is ruled by the temperature dependence of adatom diffusion rate and GaAs-GaP intermixing. The band alignment of pseudomorphic GaAs/GaP QW and GaAsP/GaP SAQDs is shown to be of type II, in contrast to that of fully relaxed GaAs/GaP SAQDs, which have the band alignment of type I with the lowest electronic states at the indirect L valley of the GaAs conduction band.
Ti-doped hematite nanostructures for solar water splitting with high efficiency
Authors: Deng Jiujun , Zhong Jun , Pu Aiwu , Zhang Duo , Li Ming , Sun Xuhui , Lee Shuit-Tong
Published: October 2012

Ti-doped hematite nanostructures have been synthesized for efficient solar water splitting by adding TiCN as the Ti precursor in a hydrothermal method. Ti-doped hematite nanostructures show an urchin-like morphology with nano feature size, which increases the effective surface area compared to undoped nanostructures. A remarkable plateau photocurrent density value of 3.76 mA/cm2 has been observed for Ti-doped nanostructures under standard illumination conditions in 1 M NaOH electrolyte, which is 2.5 times higher than that for undoped nanostructures (1.48 mA/cm2). The photocurrent at 1.23 V vs. RHE (1.91 mA/cm2) is also enhanced to be over 2 times higher than that for undoped nanostructures (0.87 mA/cm2). X-ray photoelectron spectroscopy and x-ray absorption spectroscopy have been used to investigate the electronic structure of Ti-doped hematite, which suggest the increased donor density of hematite by Ti doping. The remarkable plateau current density in Ti-doped hematite nanostructures can be attributed to both the favorable urchin-like morphology and the Ti doping.
Protocol for classical molecular dynamics simulations of nano-junctions in solution
Authors: Gkionis Konstantinos , Rungger Ivan , Sanvito Stefano , Schwingenschlögl Udo
Published: October 2012

Modeling of nanoscale electronic devices in water requires the evaluation of the transport properties averaged over the possible configurations of the solvent. They can be obtained from classical molecular dynamics for water confined in the device. A series of classical molecular dynamics simulations is performed to establish a methodology for estimating the average number of water molecules N confined between two static and semi-infinite gold electrodes. Variations in key parameters of the simulations, as well as simulations with non-static infinite gold surfaces of constant area and with anisotropically fluctuating cell dimensions lead to less than 1% discrepancies in the calculated N. Our approach is then applied to a carbon nanotube placed between the gold electrodes. The atomic density profile along the axis separating the slabs shows the typical pattern of confined liquids, irrespective of the presence of the nanotube, while parallel to the slabs the nanotube perturbs the obtained profile.
Boron-rich plasma by high power impulse magnetron sputtering of lanthanum hexaboride
Authors: Oks Efim M. , Anders André
Published: October 2012

Boron-rich plasmas have been obtained using a LaB6 target in a high power impulse sputtering (HiPIMS) system. The presence of 10B+, 11B+, Ar2+, Ar+, La2+, and La+ and traces of La3+, 12C+, 14N+, and 16O+ have been detected using an integrated mass and energy spectrometer. Peak currents as low as 20 A were sufficient to obtain plasma dominated by 11B+ from a 5 cm planar magnetron. The ion energy distribution function for boron exhibits an energetic tail extending over several 10 eV, while argon shows a pronounced peak at low energy (some eV). This is in agreement with models that consider sputtering (B, La) and gas supply (from background and “recycling”). Strong voltage oscillations develop at high current, greatly affecting power dissipation and plasma properties.
Temperature-dependent electron transport in ZnO micro/nanowires
Authors: Li Xin , Qi Junjie , Zhang Qi , Zhang Yue
Published: October 2012

Temperature dependent electron transport properties of individual ZnO mirco/nanowires from 293 K to 473 K were investigated by a four-probe method, and the size dependence of activation energy was studied. The conductivity increased with the increasing temperature, which was attributed to the thermal activations of donors: shallow donors and deep donors. The activation energy related to shallow donors was effectively independent of the radius, suggesting that it was associated with the surface conduction channel of ZnO wire, while a nearly inverse dependence of the activation energy of deep donors on the wire diameter may result from the dielectric confinement effect.
Optical transduction of E. Coli O157:H7 concentration by using the enhanced Goos-Hänchen shift
Authors: Sun Jingjing , Wang Xianping , Yin Cheng , Xiao Pingping , Li Honggen , Cao Zhuangqi
Published: October 2012

Within the symmetrical metal-cladding waveguide structure, the optical transduction of the E. coli O157:H7 concentration by using the enhanced Goos-Hänchen (GH) shift is demonstrated to be an advantageous alternative over those evanescent wave-based biosensors. The experimental results indicate that the interaction between the analyte and the excited ultrahigh order modes (in the form of the oscillating wave) is the dominant reason leading to ultrahigh sensitivity. On the condition that the intrinsic damping is well-matched with the radiative damping, the giant GH shift (hundreds of micrometers) offers a higher sensitivity than the regular measurement of reflected light intensity. The transduction limit of E. Coli O157:H7 concentration about 100 cfu ml−1 is achieved.
Effect of dimensionality and morphology on polarized photoluminescence in quantum dot-chain structures
Authors: Mazur Yu. I. , Dorogan V. G. , Ware M. E. , Marega E. , Lytvyn P. M. , Zhuchenko Z. Ya. , Tarasov G. G. , Salamo G. J.
Published: October 2012

Change of the photoluminescence (PL) polarization is studied by changing the excitation intensity and temperature for aligned In(Ga)As quantum dot (QD) structures with varying inter-dot distances grown by molecular beam epitaxy on semi-insulating GaAs (100) substrates. An unusual increase of the polarization ratio is observed by increasing the temperature and/or excitation intensity throughout a low temperature (T < 70 K) and low intensity (Iex < 1 W/cm2) range. This increase as well as the general behavior of the polarized PL are the results of the exciton dynamics and the peculiarities of the system morphology. They are due to the varying inter-dot distances which change the system from zero-dimensional comprised of isolated QDs to one-dimensional comprised of wire-like structures.
Electron paramagnetic resonance and theoretical studies of Nb in 4H- and 6H-SiC
Authors: Tien Son Nguyen , Thang Trinh Xuan , Gällström Andreas , Leone Stefano , Kordina Olof , Janzén Erik , Szász Krisztián , Ivády Viktor , Gali Adam
Published: October 2012

High purity silicon carbide (SiC) materials are of interest from high-power high temperature applications across recent photo-voltaic cells to hosting solid state quantum bits, where the tight control of electrically, optically, and magnetically active point defects is pivotal in these areas. 4H- and 6H-SiC substrates are grown at high temperatures and the incorporation of transition metal impurities is common. In unintentionally Nb-doped 4H- and 6H-SiC substrates grown by high-temperature chemical vapor deposition, an electron paramagnetic resonance (EPR) spectrum with C1h symmetry and a clear hyperfine (hf) structure consisting of ten equal intensity hf lines was observed. The hf structure can be identified as due to the interaction between the electron spin S = 1/2 and the nuclear spin of 93Nb. Additional hf structures due to the interaction with three Si neighbors were also detected. In 4H-SiC, a considerable spin density of ∼37.4% was found on three Si neighbors, suggesting the defect to be a complex between Nb and a nearby carbon vacancy (VC). Calculations of the 93Nb and 29Si hf constants of the neutral Nb on Si site, NbSi0, and the Nb-vacancy defect, NbSiVC0, support previous reported results that Nb preferentially forms an asymmetric split-vacancy (ASV) defect. In both 4H- and 6H-SiC, only one Nb-related EPR spectrum has been observed, supporting the prediction from calculations that the hexagonal-hexagonal defect configuration of the ASV complex is more stable than others.
Structural transitions and unusual magnetic behavior in Mn-doped Bi1−xLaxFeO3 perovskites
Authors: Khomchenko V. A. , Troyanchuk I. O. , Karpinsky D. V. , Das S. , Amaral V. S. , Tovar M. , Sikolenko V. , Paixão J. A.
Published: October 2012

The effect of Mn doping on crystal structure and magnetic behavior of the polar antiferromagnetic and antipolar weak ferromagnetic phases of the Bi1−xLaxFeO3 system was investigated. Both reference compounds, Bi0.87La0.13FeO3 (space group R3c, tilting scheme (a−a−a−)] and Bi0.82La0.18FeO3 [space group Pnam, tilting scheme (a−a−c+)/(a−a−c−)], were shown to undergo the Mn doping induced structural phase transformation towards the average Imma (a−b0a−) symmetry. Magnetization measurements performed for the compounds with the close to maximal manganese concentration (y = 0.4) found complex temperature-dependent behavior that can be indicative of a spin-reorientation transition. Enhanced spontaneous magnetization characteristic of the Mn-enriched x = 0.13 and x = 0.18 samples at low temperature is consistent with a competitive character of the superexchange interactions peculiar to the Fe/Mn containing perovskite systems.
Fluid-structure interaction in deformable microchannels
Authors: Chakraborty Debadi , Prakash J. Ravi , Friend James , Yeo Leslie
Published: October 2012

A polydimethylsiloxane microfluidic device composed of a single microchannel with a thin flexible layer present over a short length along one side of the channel was fabricated and modelled in order to investigate the complex fluid-structure interaction that arises between a flowing fluid and a deformable wall. Experimental measurements of thin layer deformation and pressure drop are compared with predictions of two- and three-dimensional computational models that numerically solve the coupled set of equations governing both the elasticity of the thin layer and the fluid. It is shown that the two-dimensional model, which assumes the flexible thin layer comprises an infinitely wide elastic beam of finite thickness, reasonably approximates a three-dimensional model, and is in excellent agreement with experimental observations of the thin layer profile when the width of the thin layer is beyond a critical value, roughly twice the length of the thin layer.
Long-wave infrared nBn photodetectors based on InAs/InAsSb type-II superlattices
Authors: Kim H. S. , Cellek O. O. , Lin Zhi-Yuan , He Zhao-Yu , Zhao Xin-Hao , Liu Shi , Li H. , Zhang Y.-H.
Published: October 2012

Long-wave infrared InAs/InAsSb type-II superlattice nBn photodetectors are demonstrated on GaSb substrates. The typical device consists of a 2.2 μm thick absorber layer and has a 50% cutoff wavelength of 13.2 μm, a measured dark current density of 5 × 10−4 A/cm2 at 77 K under a bias of −0.3 V, a peak responsivity of 0.24 A/W at 12 μm, and a maximum resistance-area product of 300 Ω cm2 at 77 K. The calculated generation-recombination noise limited specific detectivity (D*) and experimentally measured D* at 12 μm and 77 K are 1 × 1010 cm Hz1/2/W and 1 × 108 cm Hz1/2/W, respectively.
Near-infrared enhanced carbon nanodots by thermally assisted growth
Authors: Wen Xiaoming , Yu Pyng , Toh Yon-Rui , Lee Yu-Chieh , Hsu An-Chia , Tang Jau
Published: October 2012

The near-infrared emission, matching the biological window, is conducive to biological applications. To date, most of the reported carbon nanodots emit the blue to green fluorescence and few of carbon nanodots emit the near-infrared with relatively lower efficiency. Here, we report an approach to generate or to enhance the near-infrared luminescence from the green luminescent carbon nanodots. Experiments reveal that the near-infrared emission is significantly enhanced by thermally assisted growth in vacuum, which is attributed to the formation of the larger nano-domains from the small carbon clusters at elevated temperatures.
Voltage-assisted ion reduction in liquid crystal-silica nanoparticle dispersions
Authors: Liao Shu-Wei , Hsieh Chia-Ting , Kuo Chih-Chin , Huang Chi-Yen
Published: October 2012

We demonstrate an effective method of reducing mobile ions in a silica nanoparticle (SN)-doped liquid crystal (LC) cell by alternating-current high-voltage pulse treatment (ACHVPT). In this method, the director distortion in LCs near the substrate creates a lifting force that moves the SNs toward the substrate. The moving SNs trap mobile ions in the cell bulk. After ACHVPT, the SNs and mobile ions are adsorbed onto the substrates, thereby significantly decreasing cell ion density. The ion density of the SN-doped LC cell after ACHVPT treatment is 1.5% of that of a pristine LC cell.
Single molecule labeling of an atomic force microscope cantilever tip
Authors: Liu Jianwei , Butte Manish J.
Published: October 2012

In this paper, we present a method to functionalize the very apex of an atomic force microscope cantilever with a single or a few molecules. In force spectroscopy or interaction mapping, the cantilever must be functionalized with only a few molecules to avoid noise or spurious measurements. Here, we covalently attached single molecules to the cantilever by touching it to a paper wetted with a solution of quantum dots. The paper competes with wicking up the hydrophilic surface of the tip. This method has broad applications in scanning probe microscopy where small numbers of molecules are needed on the tip.
Tunable open-circuit voltage in ternary organic solar cells
Authors: Li Hui , Zhang Zhi-Guo , Li YongFang , Wang Jizheng
Published: October 2012

Recently, there are growing interests in ternary organic solar cells due to their expected broader absorption in comparison to their counterpart binary systems. It is found that open-circuit voltage in a ternary system can be largely tuned by varying the composition ratio of two donors or two acceptors integrated in. However, there is no detailed analysis for such an interesting observation. In this paper, we fabricated ternary solar cells with one p-type polymer as donor and two mixed n-type fullerenes as acceptor, and investigated the open-circuit voltage by varying the weight ratio of the two fullerenes. A three-diode model is developed to analyze the tunable behavior of open-circuit voltage displayed in our ternary system in terms of energy loss and dark current suppression. We also discussed the tunable open-circuit voltage based on electron and hole quasi-Fermi levels.
Quasiresonant excitation of InP/InGaP quantum dots using second harmonic generated in a photonic crystal cavity
Authors: Buckley Sonia , Rivoire Kelley , Hatami Fariba , Vučković Jelena
Published: October 2012

Indistinguishable single photons are necessary for quantum information processing applications. Resonant or quasiresonant excitation of single quantum dots provides greater single photon indistinguishability than incoherent pumping, but is also more challenging experimentally. Here, we demonstrate high signal to noise quasiresonant excitation of InP/InGaP quantum dots. The excitation is provided via second harmonic generated from a telecommunications wavelength laser resonant with the fundamental mode of a photonic crystal cavity, fabricated at twice the quantum dot transition wavelength. The second harmonic is generated using the χ(2) nonlinearity of the InGaP material matrix.
Internal friction and dynamic modulus in Ru-50Nb ultra-high temperature shape memory alloys
Authors: Dirand L. , Nó M. L. , Chastaing K. , Denquin A. , San Juan J.
Published: October 2012

The martensitic transformations in ultra-high temperature Ru-50Nb shape memory alloys have been studied by internal friction and dynamic modulus measurements. Two successive transformations from the high temperature cubic β phase to a tetragonal β′ martensite and then to another monoclinic β″ martensite have been found. Both transformations exhibit a sharp internal friction peak and a clear softening of the dynamic modulus, being a signature of the thermo-elastic martensitic transformations. In addition, a pseudo relaxation peak strongly dependent on time has been found and analyzed, concluding that it is linked to a pinning effect of martensite interfaces by point defects.
A stochastic model of cascades in two-dimensional turbulence
Authors: Ditlevsen Peter D.
Published: October 2012

The dual cascade of energy and enstrophy in 2D turbulence cannot easily be understood in terms of an analog to the Richardson-Kolmogorov scenario describing the energy cascade in 3D turbulence. The coherent upscale and downscale fluxes point to non-locality of interactions in spectral space, and thus the specific spatial structure of the flow could be important. Shell models, which lack spatial structure and have only local interactions in spectral space, indeed fail in reproducing the correct scaling for the inverse cascade of energy. In order to exclude the possibility that non-locality of interactions in spectral space is crucial for the dual cascade, we introduce a stochastic spectral model of the cascades which is local in spectral space and which shows the correct scaling for both the direct enstrophy and the inverse energy cascade.
Dynamic spin injection into chemical vapor deposited graphene
Authors: Patra A. K. , Singh S. , Barin B. , Lee Y. , Ahn J.-H. , del Barco E. , Mucciolo E. R. , Özyilmaz B.
Published: October 2012

We demonstrate dynamic spin injection into chemical vapor deposition (CVD) grown graphene by spin pumping from permalloy (Py) layers. Ferromagnetic resonance measurements at room temperature reveal a strong enhancement of the Gilbert damping at the Py/graphene interface, indeed exceeding that observed in Py/platinum interfaces. Similar results are also shown on Co/graphene layers. This enhancement in the Gilbert damping is understood as the consequence of spin pumping at the interface driven by magnetization dynamics. Our observations suggest a strong enhancement of spin-orbit coupling in CVD graphene, in agreement with earlier spin valve measurements.
Branched carbon nanotube reinforcements for improved strength of polyethylene nanocomposites
Authors: Liu Ling , Zhang Lin , Lua Jim
Published: October 2012

A bio-inspired design of polyethylene nanocomposites is presented in this letter using branched carbon nanotubes (BCNTs) as reinforcements. Using coarse-grained molecular dynamics simulations, we demonstrate that the pullout strength of the proposed BCNT nanofibers can be an order of magnitude higher than that of CNT reinforcements. The drastically improved interfacial shearing strength is found to be strongly dependent on the geometry of nanofibers, the molecular weight of matrix polymers, and the pullout velocity. By analyzing the time-evolving molecular configurations of BCNT nanofibers and surrounding polymer chains, the underlying strengthening mechanisms are discussed and strategies for further improvement are suggested.
Characteristic microvessel relaxation timescales associated with ultrasound-activated microbubbles
Authors: Chen Hong , Brayman Andrew A. , Matula Thomas J.
Published: October 2012

Ultrasound-activated microbubbles were used as actuators to deform microvessels for quantifying microvessel relaxation timescales at megahertz frequencies. Venules containing ultrasound contrast microbubbles were insonified by short 1 MHz ultrasound pulses. Vessel wall forced-deformations were on the same microsecond timescale as microbubble oscillations. The subsequent relaxation of the vessel was recorded by high-speed photomicrography. The tissue was modeled as a simple Voigt solid. Relaxation time constants were measured to be on the order of ∼10 μs. The correlation coefficients between the model and 38 data sets were never lower than 0.85, suggesting this model is sufficient for modeling tissue relaxation at these frequencies. The results place a bound on potential numerical values for viscosity and elasticity of venules.
Transport characteristics of graphene-metal interfaces
Authors: Nam Do V. , Anh Le H.
Published: October 2012

A physical model is proposed to clarify the electron transport through graphene-metal interfaces. It is based on an effective description of the coupling between the graphene π-bands and the metal sd- and d-bands. Applying this model to vertically symmetrical metal-graphene-metal structures, we show that the current-voltage characteristics can be either linear or non-linear with a negative or positive differential resistance depending on the dominance of the d-like or s-like electrons in the metal as well as the graphene-metal coupling.
Microscopic characteristics of dynamic nuclear polarization and selective nuclear depolarization at the ν=2/3 spin phase transition
Authors: Fauzi M. H. , Watanabe S. , Hirayama Y.
Published: October 2012

The ability to manipulate the nuclear spin degree of freedom in semiconductor quantum structures is necessary for development of nuclear spintronics based on solid-state systems. Here, we developed a method to selectively depolarize the nuclear spin, the 〈+Iz〉 or the 〈−Iz〉 component, residing in a GaAs quantum well specimen after dynamic nuclear polarization by applying radio frequency pulse to either spin-unpolarized or spin-polarized nuclear magnetic resonance lines obtained at the spin transition of the filling ν=2/3. Our results are evidence that the spin-unpolarized (spin-polarized) domain mediates the 〈+Iz〉 (〈−Iz〉) nuclear spin polarization.
Temperature-dependent properties of semimetal graphite-ZnO Schottky diodes
Authors: Yatskiv R. , Grym J.
Published: October 2012

Highly rectifying semimetal graphite/ZnO Schottky diodes with a low-ideality-factor (1.08 at 300 K) were investigated by temperature-dependent current-voltage measurements. The current transport was dominated by thermionic emission between 300 and 420 K and the extracted barrier height followed the Schottky-Mott relation. A Richardson constant (A** = 0.272 A cm−2K−2) extracted from the Richardson plot shows nearly linear characteristics in the temperature range 300–420 K.
Void structure in silica glass with different fictive temperatures observed with positron annihilation lifetime spectroscopy
Authors: Ono Madoka , Hara Kenta , Fujinami Masanori , Ito Setsuro
Published: October 2012

We examine voids in silica glasses with different fictive temperatures using positron annihilation lifetime spectroscopy. The pick-off annihilation lifetime of ortho-positronium increases with the fictive temperature, Tf, indicating that the void size increases. High Tf leads to high density and low degree of network polymerization so that increasing void size means that the density fluctuation of the silica glass increases with high Tf. Assuming that such density fluctuation causes light scattering, the previously reported Tf dependence of the Rayleigh scattering coefficient can be well explained by the change in void size.
Note: Particle adhesion and imaging of particle/surface breakage zone
Authors: Pettersson Torbjörn , Utsel Simon , Wågberg Lars
Published: October 2012

An AFM methodology to enable measurement of the adhesion of micrometre sized objects, having contact areas in the range of nanometre to micrometer, is reported. The method also enables imaging of the actual breakage zone on both the surface and the removed object to obtain further information regarding the breakage zone. The method is also useful for measuring consolidating systems, such as drying, curing, or annealing systems.
Urban ‘Utopias’: The Disney Stigma and Discourses of ‘False Modernity’
Authors: Koch Natalie
Published: October 2012

This paper examines the political implications of the practice of framing mega urban development projects with the language of ‘utopia’ or ‘Disney’. Through a case study of Kazakhstan's new capital, Astana, I argue that the stigmatizing language of ‘utopia’ is a highly political bordering practice, defining the ‘imaginary’ and the ‘real.’ Coupled with ethnographic data from fieldwork in Kazakhstan between 2009 and 2011, I perform a textual analysis of English and German language press coverage of Astana, and demonstrate how narratives of ‘false modernity’ and ‘utopia’ have become the dominant way of reading and writing about the city. Although often critical of the project as a sign of the President Nursultan Nazarbayev's ‘megalomania,’ this coverage obscures more complex geographies of power and state—society relations in the independent state. Symptomatic of liberal (ie, top-down, one-dimensional) understandings of power, the hegemonic discourse simultaneously reinscribes the state's ‘coherence’ and erases the lived realities and agencies of ordinary citizens, while obscuring the more complicated political—economic relations that condition and give rise to ‘spectacular’ urban development projects.
Governance and the Geography of Authority: Modalities of Authorisation and the Transnational Governing of Climate Change
Authors: Bulkeley Harriet
Published: October 2012

Within debates about the emergence and nature of governance, it has become commonplace to debate the whereabouts and possibilities of authority. Traditionally, authority is conceived as a property of some actor or institution and is regarded as divisible over time and space. Drawing on theories of power, in which it is regarded as constitutive of social relations, this paper proposes an alternative account of authority in which it is seen as one form of power that can be enacted towards three distinct purposes—instrumental (as consent), associational (as consensus), and governmental (as concord)—involving particular forms of recognition and compliance, and mediated through distinct sociospatial relations. The paper examines the potential of such an approach through exploring the workings of authority in transnational climate-change governance. Given the sustained debates within this field concerning the shifting geographies of authority between public/private actors and across different political spaces, this provides an important test of the explanatory value of this approach. The analysis suggests that, while these modes are not mutually exclusive, they orchestrate the ‘will to govern’ in significantly different ways, with important implications both for how governing is accomplished and for the geographies of global environmental governance.
From ‘New Materialism’ to ‘Machinic Assemblage’: Agency and Affect in IKEA
Authors: Roberts Tom
Published: October 2012

New materialist theory has destabilized the figure of the sovereign subject by exploring matter's capacity to pose questions on its own terms. Such critique engages a growing concern for embodied modes of agency that exceed the intentions of human subjects. Exploring nonhuman agency through material capacities, ‘affect’ is a concept that poses new questions to the everyday circulations and assemblages of well-known sites. Viewed through an affectual lens, contemporary sites of consumption exceed their economic conditions of emergence, requiring approaches that acknowledge the ontological import of material reorganisation. By revisiting the work of Felix Guattari, this paper enacts a ‘machinic’ engagement with IKEA, situating a fundamentally engineered assemblage within virtual ecologies of nonhuman relation. Framed by a sustained ethnographic encounter with IKEA Bristol, I explore machinic assemblages of vibrations, molecules, and things. Through these material configurations, the IKEA assemblage makes uncertain interventions upon a ‘nonorganic life’, continually experimenting with a body's capacity to affect and to be affected. Guattari's project displaces the emergence of the new away from the interiority of a subject, such that change takes place through a diversity of machinic connections. To address the fundamental political question of change, politics must look beyond the molar semiotics of subjects and objects, to engage with more subtle recompositions of affective capacities.
The Limits to Libertarian Paternalism: Two New Critiques and Seven Best-Practice Imperatives
Authors: Gill Nick , Gill Matthew
Published: October 2012

Behavioural economists argue that humans are predictably irrational in various ways, as a result of which there appears to be a role for public policy in improving their decision making. We of er a sympathetic critique of this so-called ‘libertarian paternalist’ approach. As well as reviewing existing critiques, we present two new arguments. First, we question whether policies which are not beneficial to the individuals they target can be justified within a libertarian paternalist framework, even if they contribute to the social good. Second, we highlight the potentially adverse consequences of poorly targeted libertarian paternalist interventions. In the penultimate section we bring together the existing critiques and the new arguments to of er seven best-practice imperatives for the careful application of these powerful, but easily misused, tools of government. We conclude with a brief reflection on what freedom might mean in the context of libertarian paternalist governance.
Is There a Link between Globalization and Governance?
Authors: Ezcurra Roberto
Published: October 2012

With this paper I investigate empirically the relationship between globalization and governance. To this end, I use a measure of globalization that distinguishes the social and political dimensions of integration from the economic dimension, which allows me to adopt a broader perspective than in existing studies and to examine the effect of these three distinct dimensions of globalization on governance. The results show that those countries with higher levels of integration with the rest of the world tend on the whole to register better governance outcomes. The dimensions of globalization most robustly related with the quality of governance are economic and social integration. These findings are not affected by the inclusion in the analysis of additional explanatory variables, such as GDP per capita, the degree of ethnolinguistic fractionalization, legal origin, religion, natural resource abundance, and government size.
How Can a Cluster Policy Enhance Entrepreneurship? Evidence from the German ‘Bioregio’ Case
Authors: Champenois Claire
Published: October 2012

I investigate the mechanisms through which a cluster policy can enhance entrepreneurship defined as new venture creation. The paper is based on the study of a cluster policy (‘BioRegio’) that strongly simulated new firm creation in biotechnology in Germany after 1996. The process induced by BioRegio at the territory level is analyzed over a ten-year period (1995–2004). I identify a three-step social mechanism through which a cluster policy can enhance entrepreneurship. The presented results strengthen the literature on cluster policies and clusters on the specif c issue of entrepreneurship: four main contributions are suggested.
Why is Intersectoral Cooperation Difficult to Maintain? Insights from French Cluster Policy
Authors: Younès Dima
Published: October 2012

Intersectoral cooperation is increasingly perceived as important to regional renewal. Yet, studies of local cooperation generally show that few ties exist among actors from different sectors. However, we know little about the mechanisms behind this lack, which exists despite efforts by policy makers and, sometimes, despite the desires of upper-level managers within firms. I attempt to examine mechanisms that might explain this lack of intersectoral partnerships. To this end, I will use a study of the cluster at Plateau de Saclay (in the Paris suburbs), which was founded in response to the French government's Pôle de compétitivité policy. The paper shows that, in order to understand these mechanisms, it is necessary to examine both local arrangements and employees' work within firms. The former explains dynamics of inclusion and exclusion, while the latter sheds light on the way firm strategy is constructed. Local arrangements have made it difficult to build intersectoral partnerships. In some cases policy does succeed in making firms from different sectors cooperate, but these partnerships are difficult to maintain—a problem that results from negotiations inside large firms with conflicting economic goals and a lack of experience in measuring knowledge benefits.
Policy Learning and the ‘Cluster-Flavoured Innovation Policy’ in Finland
Authors: Sotarauta Markku
Published: October 2012

With this paper I aim to shed light on the attempts that have been made to adjust Finnish policy making to the changes in the global technoeconomic environment, as well as to the meta-rationales behind the evolving cluster-flavoured innovation (CFI) policies. Policy learning is discussed with reference to the main cluster and innovation policy changes in Finland and related conceptual development. My main aim is to paint an overall picture of Finnish CFI polices and learning related to them as well as to analyse how efforts to redesign the policies have been unfolding over the past twenty years. This paper is based on (a) secondary data (ie, earlier studies and reports on the Finnish cluster and innovation policies) and (b) data from two empirical studies.
Habitat Associations of Fish Species of Greatest Conservation Need at Multiple Spatial Scales in Wadeable Iowa Streams
Authors: Sindt Anthony R. , Quist Michael C. , Pierce Clay L.
Published: October 2012

Fish and habitat data were collected from 84 wadeable stream reaches in the Mississippi River drainage of Iowa to predict the occurrences of seven fish species of greatest conservation need and to identify the relative importance of habitat variables measured at small (e.g., depth, velocity, and substrate) and large (e.g., stream order, elevation, and gradient) scales in terms of their influence on species occurrences. Multiple logistic regression analysis was used to predict fish species occurrences, starting with all possible combinations of variables (5 large-scale variables, 13 small-scale variables, and all 18 variables) but limiting the final models to a maximum of five variables. Akaike's information criterion was used to rank candidate models, weight model parameters, and calculate model-averaged predictions. On average, the correct classification rate (CCR = 80%) and Cohen's kappa (κ = 0.59) were greatest for multiple-scale models (i.e., those including both large-scale and small-scale variables), intermediate for small-scale models (CCR = 75%; κ = 0.49), and lowest for large-scale models (CCR = 73%; κ = 0.44). The occurrence of each species was associated with a unique combination of large-scale and small-scale variables. Our results support the necessity of understanding factors that constrain the distribution of fishes across spatial scales to ensure that management decisions and actions occur at the appropriate scale.

Received January 29, 2012; accepted July 18, 2012
Do Anglers Know What They Catch? Identification Accuracy and Its Effect on Angler Survey-Derived Catch Estimates
Authors: Page Kevin S. , Zweifel Richard D. , Carter George , Radabaugh Nick , Wilkerson Michael , Wolfe Matthew , Greenlee Michael , Brown Kipp
Published: October 2012

Angler surveys are reliant on the ability of anglers to accurately report various aspects of their fishing trips. Misidentification of sport fishes has been postulated as a source of error among angler surveys but has received little attention. We evaluated the overall ability of anglers to identify sport fishes common to Ohio and the potential impacts on catch estimates derived from angler surveys. During angler surveys conducted on lakes and reservoirs (2007, n = 34) and Ohio River tailwaters (2010, n = 3), anglers were presented with artist-rendered images of 18 different sport fishes common to these waters. Anglers (lake and reservoir, n = 2,442; Ohio River, n = 458) were asked to identify sport fish by their common name. On average, anglers correctly identified sport fishes 42% of the time, but accuracy varied widely among species (lake and reservoir, range = 4.4–85.1%; Ohio River, range = 9.4–71.8%), with greater accuracy exhibited for the most common species (e.g., largemouth bass Micropterus salmoides). However, by grouping angler responses into species groups (e.g., black bass Micropterus spp., sunfish Lepomis spp.) angler identification of sport fishes was more reliable (lake and reservoir, mean = 83.4%; Ohio River, mean = 83.8%). Using these estimates of angler accuracy, we simulated the potential error in sport fish catch estimates using data from an angler survey conducted at one Ohio reservoir. These results suggested that misidentification error may result in a substantial error in catch estimates. A survey of North American fisheries management agencies regarding angler surveys and angler sport fish identification revealed that the majority of agencies group similar species for analysis and cited species misidentification by anglers as the primary reason for doing so.

Received April 19, 2012; accepted August 17, 2012
Effects of van der Waals interactions on the nonlinear vibration of multi-layered graphene sheets
Authors: Arghavan S , Singh A V
Published: October 2012

This paper is concerned with the forced nonlinear vibration of multi-layered graphene sheets modelled at the atomic level by the lattice structure approach. In this, the covalent bond between two carbon atoms is assumed as a structural member with prescribed physical and material properties. An atom is treated as a nodal point with its own mass and six degrees of freedom. The highly nonlinear van der Waals interaction between adjacent graphene layers is fully incorporated in the model by placing it in the force vector. This adjustment significantly reduces the computational hardships due to nonlinearity and increases the efficiency of the method. Newmark's direct integration method is modified to address the nonlinearity in the load vector and used for the solution of the matrix equation governing the motion of the multi-layered graphene sheet. Double-layered square graphene with simply supported and clamped boundary conditions is analysed to examine the out-of-plane and in-plane vibrational characteristics. Also, in order to illustrate the applicability of the numerical method, analyses are carried out with the first- and second-order Taylor series approximations of the van der Waals interactions, influence of which is found to be quite significant in the bending modes of vibration, but it essentially does not have a role in the in-plane modes. The numerical method developed herein is quite appropriate with reference to the structural formation at the atomic scale and also more efficient than previous computational approaches by others.
On the ill-posedness for a nonlinear Schrödinger-Airy equation
Authors: Carvajal Xavier
Published: October 2012

Using ideas of Kenig, Ponce and Vega and an explicit solution with two parameters, we prove that the solution map of the initial value problem for a particular nonlinear Schrödinger-Airy equation fails to be uniformly continuous.

Also, we will approximate the solution to the nonlinear Schrödinger-Airy equation by the solution to the cubic nonlinear Schrödinger equation and prove ill-posedness in a more general case than above. This method was originally introduced by Christ, Colliander and Tao for the modified Korteweg-de Vries equation.

Finally, we consider the general case and we prove ill-posedness for all values of the parameters in the equation.
Inferred and Stated Attribute Non‐attendance in Food Choice Experiments
Authors: Scarpa Riccardo , Zanoli Raffaele , Bruschi Viola , Naspetti Simona
Published: October 2012

We review the current literature on attribute non‐attendance in stated choice and use data from beef and chicken choice experiments using both inference and the respondents’ own statements. Inference is based on panel data analysis by mixed logit models of choice with both discrete and continuous mixtures of coefficients, and is conditional on the observed pattern of choice. Information from respondent statements on non‐attendance is directly embedded in the specification of the indirect utility function. Results show no clear winner between the inferential approaches, but the inference based on constrained latent class panel models better matches the observed data.
Human protein–protein interaction prediction by a novel sequence-based co-evolution method: co-evolutionary divergence
Authors: Hsin Liu Chia , Li Ker-Chau , Yuan Shinsheng
Published: October 2012

Motivation: Protein–protein interaction (PPI) plays an important role in understanding gene functions, and many computational PPI prediction methods have been proposed in recent years. Despite the extensive efforts, PPI prediction still has much room to improve. Sequence-based co-evolution methods include the substitution rate method and the mirror tree method, which compare sequence substitution rates and topological similarity of phylogenetic trees, respectively. Although they have been used to predict PPI in species with small genomes like Escherichia coli, such methods have not been tested in large scale proteome like Homo sapiens.

Result: In this study, we propose a novel sequence-based co-evolution method, co-evolutionary divergence (CD), for human PPI prediction. Built on the basic assumption that protein pairs with similar substitution rates are likely to interact with each other, the CD method converts the evolutionary information from 14 species of vertebrates into likelihood ratios and combined them together to infer PPI. We showed that the CD method outperformed the mirror tree method in three independent human PPI datasets by a large margin. With the arrival of more species genome information generated by next generation sequencing, the performance of the CD method can be further improved.

Availability: Source code and support are available at http://mib.stat.sinica.edu.tw/LAP/tmp/CD.rar.

Contact:  syuan@stat.sinica.edu.tw

Supplementary information:  Supplementary data are available at Bioinformatics online.
Discriminative modelling of context-specific amino acid substitution probabilities
Authors: Angermüller Christof , Biegert Andreas , Söding Johannes
Published: October 2012

Motivation: Protein sequence searching and alignment are fundamental tools of modern biology. Alignments are assessed using their similarity scores, essentially the sum of substitution matrix scores over all pairs of aligned amino acids. We previously proposed a generative probabilistic method that yields scores that take the sequence context around each aligned residue into account. This method showed drastically improved sensitivity and alignment quality compared with standard substitution matrix-based alignment.

Results: Here, we develop an alternative discriminative approach to predict sequence context-specific substitution scores. We applied our approach to compute context-specific sequence profiles for Basic Local Alignment Search Tool (BLAST) and compared the new tool (CS-BLASTdis) to BLAST and the previous context-specific version (CS-BLASTgen). On a dataset filtered to 20% maximum sequence identity, CS-BLASTdisis was 51% more sensitive than BLAST and 17% more sensitive than CS-BLASTgenin, detecting remote homologues at 10% false discovery rate. At 30% maximum sequence identity, its alignments contain 21 and 12% more correct residue pairs than those of BLAST and CS-BLASTgen, respectively. Clear improvements are also seen when the approach is combined with PSI-BLAST and HHblits. We believe the context-specific approach should replace substitution matrices wherever sensitivity and alignment quality are critical.

Availability: Source code (GNU General Public License, version 3) and benchmark data are available at ftp://toolkit.genzentrum.lmu.de/pub/csblast/.

Contact:  soeding@genzentrum.lmu.de

Supplementary information:  Supplementary data are available at Bioinformatics online.