bluuebunny/crossref_metadata_2025 huggingface dataset:
The value of air quality and crime in Chile: a hedonic wage approach
Authors: LAVÍN FELIPE VÁSQUEZ , DRESDNER JORGE , AGUILAR RENATO
Published: February 2011

We estimate the implicit prices of the crime rate and airborne pollution in Chile, using spatially compensating price differentials in the housing and labor markets. We evaluate empirically the impact of different estimation strategies for the wage and rent equations, on the economic value of these two amenities. The results show that increments in the crime rate or in air pollution have a negative impact on welfare and that the estimated welfare measures and their variances are sensitive to selection bias, endogenous amenities and clustering effects. In contrast, the welfare measures do not seem to be very sensitive to the simultaneity bias.
BIASED TECHNICAL CHANGE, INTERMEDIATE GOODS, AND TOTAL FACTOR PRODUCTIVITY
Authors: Moro Alessio
Published: February 2011

In this paper I show that the intensity at which intermediate goods are used in the production process affects aggregate total factor productivity (TFP). To do this, I construct an input–output model economy in which firms produce gross output by means of a production function in capital, labor, and intermediate goods. This production function is subject, together with the standard neutral technical change, to intermediates-biased technical change. Positive (negative) intermediates-biased technical change implies a decline (increase) in the elasticity of gross output with respect to intermediate goods. In equilibrium, this elasticity appears as an explicit part of TFP in the value added aggregate production function. In particular, when the elasticity of gross output with respect to intermediates increases, aggregate TFP declines. I use the model to quantify the impact of intermediates-biased technical change for measured TFP growth in Italy. The exercise shows that intermediates-biased technical change can account for the productivity slowdown observed in Italy from 1994 to 2004.
Healthy eating in early years settings: a review of current national to local guidance for North West England
Authors: Bristow Katie , Capewell Simon , Abba Katharine , Goodall Mark , Lloyd-Williams Ffion
Published: February 2011

Objective

To determine the extent to which national and local UK guidelines for the early years sector address key recommendations for encouraging healthy eating based on best available evidence.

Design

Phase 1 comprised a literature review to identify new evidence to assess current relevance of the Caroline Walker Trust (CWT) ‘Eating well for under-5 s in child care’ guidelines. Phase 2 assessed the completeness of seven local to national-level government guidelines by comparison with the ‘gold standard’ CWT guidelines.

Setting

Desk-based review using secondary data.

Subjects

Research literature and statutory guidelines on healthy eating in early years settings.

Results

Phase 1 retrieved seventy-five papers, of which sixty were excluded as they addressed compliance with nutritional and food-based standards only. One report examined a social marketing tool and was deemed too narrow. The remaining fourteen documents assessed interventions to encourage healthy eating in early years settings. Following quality assessment, seven documents were included. Nine key recommendations were identified: (i) role of government; (ii) early years setting policy/guidelines; (iii) training; (iv) menu planning; (v) parents; (vi) atmosphere and encouragement; (vii) learning through food; (viii) sustainability; and (ix) equal opportunities. Phase 2 identified that all seven guidelines included the nine key recommendations but sporadic cover of sub-key recommendations.

Conclusions

More detail is needed on how early years settings can encourage children to eat healthily. Research is required to develop second-layer guidance for interactive materials. Clear processes of communication and support for parents are required. Ways food relates to children's wider learning and social development need further thought, requiring collaboration between the Department of Health and the Department for Education.
A Review of Ultrastructural and Ultracytochemical Studies of Infection Processes in Some Plant Wilt Diseases: The Opaque Matter Extensively Involved, Its Links with Pathogen Elements, Insights into Its Nature
Authors: Ouellette G.B. , Charest P.M. , Chamberland H.
Published: February 2011

The present review is based on results of several years of investigation on the pathogenesis of plant wilt diseases using for one of the main aspects, several labeling techniques at the ultrastructural level: autoradiography with3H-thymidine; gold-tagged lectins, enzymes, polyclonal, and monoclonal antibodies. Thus, opaque matter (OM), labeling for DNA with the appropriate markers, can be abundant in and associated with host tissue reactions and pronounced alterations (particularly in newly differentiated xylem). The presence of structures (called P-elements) in OM, paralleled by a similar occurrence in nuclei of both the host and pathogen cells, is considered as being also indicative of a cytoplasmic nature for this OM and most likely originating from fungal elements.
Solving functional constraints by variable substitution
Authors: ZHANG YUANLIN , YAP ROLAND H. C.
Published: February 2011

Functional constraints and bi-functional constraints are an important constraint class in Constraint Programming (CP) systems, in particular for Constraint Logic Programming (CLP) systems. CP systems with finite domain constraints usually employ Constraint Satisfaction Problem(s)-based solvers which use local consistency, for example, arc consistency. We introduce a new approach which is based instead on variable substitution. We obtain efficient algorithms for reducing systems involving functional and bi-functional constraints together with other nonfunctional constraints. It also solves globally any CSP where there exists a variable such that any other variable is reachable from it through a sequence of functional constraints. Our experiments on random problems show that variable elimination can significantly improve the efficiency of solving problems with functional constraints.
Protection of plant varieties: systems across countries
Authors: Brahmi Pratibha , Chaudhary Vijaya
Published: February 2011

This study discusses some of the important aspects of laws/regulations formulated for the protection of plant varieties in Union for the Protection of New Varieties of Plants (UPOV) member states, European Community countries and India. The study also provides an insight into some of the unique features of Indian sui generis system for the protection of plant varieties. During this study, the registration of crop notified in India and in some selected UPOV member countries has been examined. Since India is not an UPOV member state, the system of plant variety protection (PVP) is independent of international scenario but aims for similar standards. The study provides useful information in order to analyse the implementation of PVP laws in UPOV member states and India. Some important features were selected for carrying out a comparative analysis. These include Intellectual Property Rights protection (patent/breeder's right), types of varieties protected, methods of testing, criteria for protection, duration of protection, exemptions (researcher/farmer's exemption), infringement and penalty and compulsory license.
Strategies for conservation of germplasm in endemic redwoods in the face of climate change: a review
Authors: Ahuja M. R.
Published: February 2011

This study reviews the various conservation strategies applied to the four redwood species, namely coast redwood (Sequoia sempervirens), Sierra redwood or giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides) and South American redwood or alerce (Fitzroya cupressoides), which are endemic in the USA, China and South America, respectively. All four redwood genera belong to the familyCupressaceae; they are monospecific, share a number of common phenotypic traits, including red wood, and are threatened in their native ranges due to human activity and a changing climate. Therefore, the management objective should be to conserve representative populations of the native species with as much genetic diversity as possible for their future survival. Those representative populations exhibiting relatively high levels of genetic diversity should be selected for germplasm preservation and monitored during the conservation phase by using molecular markers.In situandex situstrategies for the preservation of germplasm of the redwoods are discussed in this study. A holisticin situgene conservation strategy calls for the regeneration of a large number of diverse redwood genotypes that exhibit adequate levels of neutral and adaptive genetic variability, by generative and vegetative methods for their preservation and maintenance in their endemic locations. At the same time, it would be desirable to conserve the redwoods in newex situreserves, away from their endemic locations with similar as well as different environmental conditions for testing their growth and survival capacities. In addition, otherex situstrategies involving biotechnological approaches for preservation of seeds, tissues, pollen and DNA in genebanks should also be fully exploited in the face of global climate change.
Pandora's box?: humanitarian intervention and international law
Authors: Hehir Aidan
Published: February 2011

The three books reviewed here all address the question of the efficacy of international law and advance concerns about its future trajectory, albeit in contrasting ways. As has been well documented, the role of international law – specifically in the regulation of the use of force – has undergone significant scrutiny in the post-Cold War era. To a much greater extent than during the Cold War, contemporary conflicts and crises are invariably discussed with reference to international law, and the legality of a particular use of force has become a significant factor in assessing its legitimacy; one need only think of the importance placed on the legality of the 2003 invasion of Iraq. This increase in prominence suggests that international law has become more important, and unsurprisingly those used to the discipline's previous role as exotic curio have welcomed this sudden promotion (Robertson, 2000).
Optimization criteria for power amplifiers
Authors: Sombrin Jacques B.
Published: February 2011

This paper describes existing and new criteria for comparison and optimization of non-linear power amplifiers such as RF or microwave transmitters. In addition to intermodulation, receiver noise, and losses in the transmission system, the proposed new criteria take into account efficiency or consumed power. This results in the global optimization of a combined signal-to-noise-plus-intermodulation ratio as a function of saturated or nominal power but also consumed or dissipated power. Saturated power is limited by available technology. Consumed power and dissipated power are some of the main constraints in telecommunication satellite payloads, mobile phone handsets, and RFID (Radio Frequency IDentification). Another constraint comes from the limited size of antennas, which limits the system equivalent isotropic radiated power and gain-to-temperature ratio. With the proposed criteria the designer will be able to compare different amplifier technologies and to optimize the design and operating point of each stage of a multistage amplifier or a linearizer for a given amplifier. Interference from same or other systems is also introduced in the optimization through the use of signal-to-noise-plus-IM-plus-interference ratio criteria.
Environmental forcings of Paleogene Southern Ocean dinoflagellate biogeography
Authors: Bijl Peter K. , Pross Jörg , Warnaar Jeroen , Stickley Catherine E. , Huber Matthew , Guerstein Raquel , Houben Alexander J. P. , Sluijs Appy , Visscher Henk , Brinkhuis Henk
Published: February 2011

Despite warm polar climates and low meridional temperature gradients, a number of different high‐latitude plankton assemblages were, to varying extents, dominated by endemic species during most of the Paleogene. To better understand the evolution of Paleogene plankton endemism in the high southern latitudes, we investigate the spatiotemporal distribution of the fossil remains of dinoflagellates, i.e., organic‐walled cysts (dinocysts), and their response to changes in regional sea surface temperature (SST). We show that Paleocene and early Eocene (∼65–50 Ma) Southern Ocean dinocyst assemblages were largely cosmopolitan in nature but that a distinct switch from cosmopolitan‐dominated to endemic‐dominated assemblages (the so‐called “transantarctic flora”) occurred around the early‐middle Eocene boundary (∼50 Ma). The spatial distribution and relative abundance patterns of this transantarctic flora correspond well with surface water circulation patterns as reconstructed through general circulation model experiments throughout the Eocene. We quantitatively compare dinocyst assemblages with previously published TEX86–based SST reconstructions through the early and middle Eocene from a key locality in the southwest Pacific Ocean, ODP Leg 189 Site 1172 on the East Tasman Plateau. We conclude that the middle Eocene onset of the proliferation of the transantarctic flora is not linearly correlated with regional SST records and that only after the transantarctic flora became fully established later in the middle Eocene, possibly triggered by large‐scale changes in surface‐ocean nutrient availability, were abundances of endemic dinocysts modulated by regional SST variations.
Efficacy and Safety of CP‐945,598, a Selective Cannabinoid CB1 Receptor Antagonist, on Weight Loss and Maintenance
Authors: Aronne Louis J. , Finer Nick , Hollander Priscilla A. , England Richard D. , Klioze Solomon S. , Chew Robert D. , Fountaine Robert J. , Powell Coralie M. , Obourn John D.
Published: February 2011

Three double‐blind, placebo‐controlled, three‐parallel‐group, multicenter phase 3 trials were conducted to assess the efficacy and safety of CP‐945,598 for weight loss and weight‐loss maintenance. Two trials were designed to be 2 years in duration (in obese and overweight patients) and one as a 1‐year study (in obese and overweight patients with type 2 diabetes). However, the 2‐year trials and the CP‐945,598 development program were terminated before completion due to changing regulatory perspectives of CB1 receptor‐related drugs. In total, 1,253 and 2,536 participants in the two 2‐year multinational and North American studies were randomized to 10‐mg CP‐945,598 (n = 360; 718); 20‐mg CP‐945,598 (n = 534, 1,084) and placebo (n = 359, 734), respectively; and 975 participants were randomized to 10‐mg CP‐945,598 (n = 318); 20‐mg CP‐945,598 (n = 320); and placebo (n = 337) in the 1‐year multinational diabetes trial. Baseline demographics were similar between treatment groups within each trial. One year of treatment with CP‐945,598 resulted in a dose‐related mean percentage reduction from baseline body‐weight in all trials. A significant proportion of all participants also achieved 5% and 10% weight loss after 1 year. In participants with mainly well‐controlled type 2 diabetes, the combination of lifestyle and CP‐945,598 induced substantial improvements in glycemic control. The most frequent adverse events (AEs) for CP‐945,598 were: diarrhea, nausea, nasopharyngitis, and headache. Self‐reported experiences of anxiety and suicidal thoughts were higher with CP‐945,598 than placebo, as were the incidence of depression and depressed mood. However, the reported increases in psychiatric symptoms were not consistently dose dependent.
Simultaneous four-color imaging of single molecule fluorophores using dichroic mirrors and four charge-coupled devices
Authors: Haga Takanobu , Sonehara Tsuyoshi , Sakai Tomoyuki , Anazawa Takashi , Fujita Takeshi , Takahashi Satoshi
Published: February 2011

We developed a total-internal-reflection (TIR) fluorescence microscopy using three dichroic mirrors and four charge-coupled devices (CCDs) to detect simultaneously four colors of single-molecule (SM) fluorophores. Four spectrally distinct species of fluorophores (Alexa 488, Cy3, Cy5, or Cy5.5) were each immobilized on a different fused silica slide. A species of fluorophores on the slide was irradiated simultaneously, by two excitation beams from an Ar ion laser (488 and 514.5 nm) and a diode laser (642 nm) through TIR on the slide surface. Fluorescence emitted from the fluorophores was spectrally resolved into four components by the dichroic mirrors, and four images were generated from them simultaneously and continuously, with the four CCDs at a rate of 10 Hz. A series of images was thus obtained with each CCD. Fluorescence spots for a species were observed mainly in the series of images recorded by its respective-color CCD. In the first image in the series, we picked out the spots as continuous pixel regions that had the values greater than a threshold. Then we selected only those spots that exhibited single-step photobleaching and regarded them as SM fluorescence spots. Pixel values of SM fluorescence spots widely differed. Some SM fluorophores had pixel values smaller than the threshold, and were left unpicked. Assuming the pixel values of SM fluorescence spots differed with a Gaussian profile, we estimated the ratios of unpicked fluorophores to be less than 20% for all the species. Because of the spectral overlaps between species, we also observed cross-talk spots into CCDs other than the respective-color CCDs. These cross-talk SM fluorescence spots can be mistaken for correct species. We thus introduced the classification method and classified SM fluorescence spots into correct species in accordance with two kinds of four-dimensional signal vectors. The error rates of fluorophore classification were estimated to be less than 3.2% for all the species. Our system is suitable for the biological studies that desire to simultaneously monitor the four colors of SM fluorophores.
Robust zero-averaged wave-number gap inside gapped graphene superlattices
Authors: Wang Li-Gang , Chen Xi
Published: February 2011

In this paper, the electronic band structures and its transport properties in gapped graphene superlattices, with one-dimensional periodic potentials of square barriers, are systematically investigated. It is found that a zero-averaged wave-number (zero-k¯) gap is formed inside gapped graphene-based superlattices, and the condition for obtaining such a zero-k¯ gap is analytically presented. The properties of this zero-k¯ gap including its transmission, conductance and Fano factor are studied in detail. Finally, it is revealed that the properties of the electronic transmission, conductance, and Fano factor near the zero-k¯ gap are very insensitive to structural disorder for finite graphene-based periodic-barrier systems.
Intense near-infrared and midinfrared luminescence from the Dy3+-doped GeSe2–Ga2Se3–MI (M=K, Cs, Ag) chalcohalide glasses at 1.32, 1.73, and 2.67 μm
Authors: Ren Jing , Wagner Tomas , Bartos Miroslav , Frumar Miloslav , Oswald Jiri , Kincl Miloslav , Frumarova Bozena , Chen Guorong
Published: February 2011

The intense 1.32, 1.73, and 2.67 μm near-infrared and midinfrared emissions were observed from the Dy3+-doped GeSe2–Ga2Se3–MI (M=K, Cs, Ag) chalcohalide glasses. These glasses are red light transparent therefore can be pumped by a semiconductor lasers operating at ∼808 nm. The 2.67 μm emission has not been reported yet which corresponds to an absorption minimum in fluoride fibers and can be very useful for long distance communications. The intensity of emissions is very sensitive to the local chemical environment of Dy3+ ions embedded in these metal halide modified glasses. A plausible correspondence between the emission intensity and the average oscillator strength was found.
Size effects and origin of easy-axis in nickel nanowire arrays
Authors: Kartopu G. , Yalçın O. , Choy K.-L. , Topkaya R. , Kazan S. , Aktaş B.
Published: February 2011

High quality compact Ni nanowire (NW) arrays with aspect ratios (wire length/diameter) varying between 70–171 for a wire length of ∼6 μm, and between 3–400 for a constant wire diameter of 60 nm were successfully grown by direct current electrodeposition into free standing porous alumina templates having a lattice constant, i.e., interpore distance, of 105 nm. The NWs have been investigated using a combination of scanning- and transmission-electron microscopies, selected-area electron diffraction, x-ray diffraction analysis, ferromagnetic resonance (FMR), and vibration sample magnetometer techniques at room temperature. Microscopic and diffraction results show that the wires are uniform and mostly single-crystalline, being 220-oriented along the growth direction. Magnetic properties of samples are heavily dependent on the wire length as well as the diameter or packing factor, P (the volume fraction of wires/template). The FMR spectra and the field orientation dependence of the resonance field values were fitted using the imaginary part of magnetic susceptibility and a dispersion relation of magnetization, including the Bloch–Bloembergen type damping term. Combined with hysteresis (M-H) results, these indicate that the preferred (easy) axis of magnetization is parallel to the NW-axis for P<33%. On the other hand, strong interwire exchange interactions are determined to supply a magnetization state with preferred axis perpendicular to the wires for samples with P>33%. Comparison with relatively thick (110 nm diameter) and loosely packed (P∼10%) Ni NW arrays suggest that the magnetization reversal mechanism could be that of curling type.
Efficient time-dependent density functional theory approximations for hybrid density functionals: Analytical gradients and parallelization
Authors: Petrenko Taras , Kossmann Simone , Neese Frank
Published: February 2011

In this paper, we present the implementation of efficient approximations to time-dependent density functional theory (TDDFT) within the Tamm–Dancoff approximation (TDA) for hybrid density functionals. For the calculation of the TDDFT/TDA excitation energies and analytical gradients, we combine the resolution of identity (RI-J) algorithm for the computation of the Coulomb terms and the recently introduced “chain of spheres exchange” (COSX) algorithm for the calculation of the exchange terms. It is shown that for extended basis sets, the RIJCOSX approximation leads to speedups of up to 2 orders of magnitude compared to traditional methods, as demonstrated for hydrocarbon chains. The accuracy of the adiabatic transition energies, excited state structures, and vibrational frequencies is assessed on a set of 27 excited states for 25 molecules with the configuration interaction singles and hybrid TDDFT/TDA methods using various basis sets. Compared to the canonical values, the typical error in transition energies is of the order of 0.01 eV. Similar to the ground-state results, excited state equilibrium geometries differ by less than 0.3 pm in the bond distances and 0.5° in the bond angles from the canonical values. The typical error in the calculated excited state normal coordinate displacements is of the order of 0.01, and relative error in the calculated excited state vibrational frequencies is less than 1%. The errors introduced by the RIJCOSX approximation are, thus, insignificant compared to the errors related to the approximate nature of the TDDFT methods and basis set truncation. For TDDFT/TDA energy and gradient calculations on Ag-TB2-helicate (156 atoms, 2732 basis functions), it is demonstrated that the COSX algorithm parallelizes almost perfectly (speedup ∼26–29 for 30 processors). The exchange-correlation terms also parallelize well (speedup ∼27–29 for 30 processors). The solution of the Z-vector equations shows a speedup of ∼24 on 30 processors. The parallelization efficiency for the Coulomb terms can be somewhat smaller (speedup ∼15–25 for 30 processors), but their contribution to the total calculation time is small. Thus, the parallel program completes a Becke3-Lee-Yang-Parr energy and gradient calculation on the Ag-TB2-helicate in less than 4 h on 30 processors. We also present the necessary extension of the Lagrangian formalism, which enables the calculation of the TDDFT excited state properties in the frozen-core approximation. The algorithms described in this work are implemented into the ORCA electronic structure system.
Infrared spectroscopy of ionized corannulene in the gas phase
Authors: Galué Héctor Alvaro , Rice Corey A. , Steill Jeffrey D. , Oomens Jos
Published: February 2011

The gas-phase infrared spectra of radical cationic and protonated corannulene were recorded by infrared multiple-photon dissociation (IRMPD) spectroscopy using the IR free electron laser for infrared experiments. Electrospray ionization was used to generate protonated corannulene and an IRMPD spectrum was recorded in a Fourier-transform ion cyclotron resonance mass spectrometer monitoring H-loss as a function of IR frequency. The radical cation was produced by 193-nm UV photoionization of the vapor of corannulene in a 3D quadrupole trap and IR irradiation produces H, H2, and C2Hx losses. Summing the spectral response of the three fragmentation channels yields the IRMPD spectrum of the radical cation. The spectra were analyzed with the aid of quantum-chemical calculations carried out at various levels of theory. The good agreement of theoretical and experimental spectra for protonated corannulene indicates that protonation occurs on one of the peripheral C-atoms, forming an sp3 hybridized carbon. The spectrum of the radical cation was examined taking into account distortions of the C5v geometry induced by the Jahn–Teller effect as a consequence of the degenerate 2E1 ground electronic state. As indicated by the calculations, the five equivalent Cs minima are separated by marginal barriers, giving rise to a dynamically distorted system. Although in general the character of the various computed vibrational bands appears to be in order, only a qualitative match to the experimental spectrum is found. Along with a general redshift of the calculated frequencies, the IR intensities of modes in the 1000–1250 cm−1 region show the largest discrepancy with the harmonic predictions. In addition to CH “in-plane” bending vibrations, these modes also exhibit substantial deformation of the pentagonal inner ring, which may relate directly to the vibronic interaction in the radical cation.
Noise-induced effects in magnetization reversal and chirality control of circular array of single-domained nanomagnets
Authors: Pankratov A. L. , Vdovichev S. N. , Nefedov I. M. , Karetnikova I. R.
Published: February 2011

The effect of noise on the process of high-speed remagnetization of vortex state of a pentagonal array of five circular magnetic nanoparticles is studied by means of computer simulation of Landau–Lifshits model. The mean switching time (MST) and its standard deviation (SD) of the reversal between the counterclockwise and clockwise vorticities have been computed. It has been demonstrated that with the reversal by the pulse with sinusoidal shape, the optimal pulse duration exists, which minimizes both the MST and the SD. Besides, both MST and SD significantly depend on the angle between the reversal magnetic field and pentagon edge, and the optimal angle roughly equals 10°. Also, it is demonstrated that the optimization of the angle, duration and the amplitude of the driving field leads to significant decrease in both MST and SD. In particular, for the considered parameters, the MST can be decreased from 60 ns to 2–3 ns. Such a chain of magnetic nanoparticles can effectively be used as an element of magnetoresistive memory, and at the temperature 300 K the stable operation of the element is observed up to rather small size of nanoparticles with the radius of 20 nm.
Modification of Pawlow’s thermodynamical model for the melting of small single-component particles
Authors: Barybin Anatoly , Shapovalov Victor
Published: February 2011

A new approach to the melting of small particles is proposed to modify the known Pawlow’s model by taking into account the transfer of material from solid spherical particles to liquid ones through a gas phase. Thermodynamical analysis gives rise to a differential equation for the melting point Tm involving such size-dependent and temperature-dependent parameters of a material as the surface tensions σs(l), molar heat of fusion ΔHm and molar volumes vs(l). Solution of this equation has shown that all the limiting cases for size-independent situations coincide with results known in the literature and our analysis of size-dependent situations gives results close to the experimental data previously obtained by other authors for some metallic particles.
Zeta determinant for Laplace operators on Riemann caps
Authors: Flachi Antonino , Fucci Guglielmo
Published: February 2011

The goal of this paper is to compute the zeta function determinant for the massive Laplacian on Riemann caps (or spherical suspensions). These manifolds are defined as compact and boundaryless D-dimensional manifolds deformed by a singular Riemannian structure. The deformed spheres, considered previously in the literature, belong to this class. After presenting the geometry and discussing the spectrum of the Laplacian, we illustrate a method to compute its zeta regularized determinant. The special case of the deformed sphere is recovered as a limit of our general formulas.
On the proper calculation of electrostatic interactions in solid-supported bilayer systems
Authors: Yeh In-Chul , Wallqvist Anders
Published: February 2011

Modeling systems that are not inherently isotropic, e.g., extended bilayers, using molecular simulation techniques poses a potential problem. Since these methods rely on a finite number of atoms and molecules to describe the system, periodic boundary conditions are implemented to avoid edge effects and capture long-range electrostatic interactions. Systems consisting of a solvated bilayer adsorbed on a solid surface and exposed to an air/vacuum interface occur in many experimental settings and present some unique challenges in this respect. Here, we investigated the effects of implementing different electrostatic boundary conditions on the structural and electrostatic properties of a quartz/water/vacuum interface and a similar quartz-supported hydrated lipid bilayer exposed to vacuum. Since these interfacial systems have a net polarization, implementing the standard Ewald summation with the conducting boundary condition for the electrostatic long-range interactions introduced an artificial periodicity in the out-of-plane dimension. In particular, abnormal orientational polarizations of water were observed with the conducting boundary condition. Implementing the Ewald summation technique with the planar vacuum boundary condition and calculating electrostatic properties compatible with the implemented electrostatic boundary condition removed these inconsistencies. This formulation is generally applicable to similar interfacial systems in bulk solution.
Thermodynamic analysis of nucleation in confined space: Generalized Gibbs approach
Authors: Schmelzer Jürn W. P. , Abyzov Alexander S.
Published: February 2011

A general thermodynamic analysis of nucleation-growth processes in confined space in initially metastable states of the ambient phase is performed based on the generalized Gibbs approach to the description of heterogeneous systems. In particular, it is shown analytically how the parameters of critical clusters and clusters in stable equilibrium with the ambient phase depend on the volume of the system for initially fixed intensive state parameters of the ambient phase. Qualitatively, the results are shown to be similar independent on the boundary conditions employed. It is demonstrated further that the behavior of systems in confined space is directly related to the kinetics of phase transformation processes in spatially extended systems, when ensembles of clusters are formed. The results of the thermodynamic analysis of cluster formation and growth in a confined space are employed then, in particular, to the derivation of kinetic equations for the description of the process of coarsening or Ostwald ripening. In the analysis of both the nucleation in confined space and the description of Ostwald ripening, no specific assumptions concerning the equations of state of the system under consideration and the number of components both in the ambient and newly evolving phases are made. Consequently, the results are of very general nature and hold always as far as the necessary condition for the possibility of a phase transformation is fulfilled.
Structural and electronic characterization of (2,33) bar-shaped stacking fault in 4H-SiC epitaxial layers
Authors: Camarda Massimo , Canino Andrea , La Magna Antonino , La Via Francesco , Feng G. , Kimoto T. , Aoki M. , Kawanowa H.
Published: February 2011

Crystallographic, electronic, and energetic analyses of the (2,33) [or (2,3,3,3) in the standard Zhadanov notation] bar-shaped stacking fault, observed in as-grown 4H-SiC epitaxial layers, are presented. The defect has been identified by means of spatially resolved microphotoluminescence (μ-PL) measurements at different emission wavelengths, focusing on the emission peak at 0.3 eV below the conduction band. Low temperature μ-PL measurements have also been performed. The defect has been identified and characterized using high resolution transmission electron microscopy. Experimental results are correlated and validated by the calculations of the Kohn–Sham electronic band structure and the defect formation energy.
Note: A simple picture of subdiffusive polymer motion from stochastic simulations
Authors: Gniewek Pawel , Kolinski Andrzej
Published: February 2011

Entangled polymer solutions and melts exhibit unusual frictional properties. In the entanglement limit self-diffusion coefficient of long flexible polymers decays with the second power of chain length and viscosity increases with 3–3.5 power of chain length.1 It is very difficult to provide detailed molecular-level explanation of the entanglement effect.2 Perhaps, the problem of many entangled polymer chains is the most complex multibody issue of classical physics. There are different approaches to polymer melt dynamics. Some of these recognize hydrodynamic interactions as a dominant term, while topological constraints for polymer chains are assumed as a secondary factor.3,4 Other theories consider the topological constraints as the most important factors controlling polymer dynamics. Herman and co-workers describe polymer dynamics in melts, as a lateral sliding of a chain along other5,6 chains until complete mutual disentanglement. Despite the success in explaining the power-laws for viscosity, the model has some limitations. First of all, memory effects are ignored, that is, polymer segments are treated independently. Also, each entanglement/obstacle is treated as a separate entity, which is certainly a simplification of the memory effect problem. In addition to that, correlated motions of segments are addressed within the framework of renormalized Rouse-chain theory,7 without calling any topological entanglements in advance. This approach leads to the generalized Langevin equation characterized by distinct memory kernels describing local and nonlocal segment correlations8–10 or to the Smoluchowski equation in which the segments’ mobility is treated as a stochastic variable.11 Both models describe the polymer segments motion at a microscopic level. An interesting alternative is to solve the integrodifferential equation for the chain relaxation with a sophisticated kernel function.12 The design of the kernel function is based on a mesoscopic description of the polymer melt. These theories explain some experimental data, although the description of the crossover between the Rouse and non-Rouse behavior is not satisfactory. Obviously, within the scope of a short note we cannot review all theoretical concepts of the polymer melt dynamics. Here we focus just on the interpretation of the observed single segment autocorrelation function.
Temperature dependent photoresponse from colloidal PbS quantum dot sensitized inorganic/organic hybrid photodiodes
Authors: Pichler S. , Rauch T. , Seyrkammer R. , Böberl M. , Tedde S. F. , Fürst J. , Kovalenko M. V. , Lemmer U. , Hayden O. , Heiss W.
Published: February 2011

Inorganic/organic hybrid photodiodes, based on a solution-processed ternary blend containing PbS quantum dots (QDs), a fullerene derivative, and a conjugated polymer, have been reported to exhibit external quantum efficiencies in the infrared of up to 51% [T. Rauch et al., Nat. Photonics 3, 332 (2009)]. Temperature dependent experiments reveal the high sensitivity of the photoresponse on the energy level alignment between the QDs and the fullerene derivative, resulting in quenching of the photoresponse at low temperatures for 5.2 nm QDs in size. With smaller QDs the optimum operation temperature is found between room temperature and 72 °C, making these photodiodes promising for various applications.
Magnetoresistance of Fe3O4-graphene-Fe3O4 junctions
Authors: Liao Zhi-Min , Wu Han-Chun , Wang Jing-Jing , Cross Graham L. W. , Kumar Shishir , Shvets Igor V. , Duesberg Georg S.
Published: February 2011

The magnetoresistance (MR) of Fe3O4-graphene-Fe3O4 junctions has been experimentally studied at different temperatures. It is found that a barrier exists at the Fe3O4/graphene interface. The existence of the interfacial barrier was further confirmed by the nonlinear I-V characteristics and nonmetallic temperature dependence of the interfacial resistance. Moreover, spin dependent transport at the interfaces contributes −1.6% MR to the whole device at room temperature and can be regulated by an external electric field.
Enhanced optical output power of green light-emitting diodes by surface plasmon of gold nanoparticles
Authors: Cho Chu-Young , Lee Sang-Jun , Song Jung-Hoon , Hong Sang-Hyun , Lee Song-Mae , Cho Yong-Hoon , Park Seong-Ju
Published: February 2011

We demonstrate the surface plasmon (SP) enhanced green light-emitting diodes (LEDs). The Au nanoparticles were embedded in the p-GaN of LEDs. The photoluminescence and electroluminescence measurements showed improved optical properties of LEDs with Au nanoparticles due to an increase in the spontaneous emission rate by resonance coupling between the excitons in multiple quantum wells and localized surface plasmons in Au nanoparticles. The optical output power of SP-enhanced green LEDs with Au nanoparticles was increased by 86% without showing degradation of the electrical characteristics of LEDs compared to LEDs without Au nanoparticles.
Magnetocapacitance effects of Pb0.7Sr0.3TiO3/La0.7Sr0.3MnO3 thin film on Si substrate
Authors: Chen Ying , Wang Genshui , Zhang Shuai , Lei Xiuyun , Zhu Junyu , Tang Xiaodong , Wang Yongling , Dong Xianlin
Published: February 2011

Pb 0.7 Sr 0.3 TiO 3 / La 0.7 Sr 0.3 MnO 3 (PST/LSMO) thin film has been deposited on Si substrate by chemical solution deposition. Obvious changes in dielectric constant and loss as functions of frequency and magnetic field were observed in PST/LSMO thin film. By applying both dc bias electric and magnetic fields, apparent dielectric anomalies were observed in the “butterfly-hysteresis” curves. These effects may be useful for practical application. The mechanism for the magnetocapacitance effects in PST/LSMO is rationalized by combining the Maxwell–Wagner capacitor model and the magnetoresistivity and magnetostriction of the LSMO.
Terahertz metasurfaces with high Q-factors
Authors: Jansen Christian , Al-Naib Ibraheem A. I. , Born Norman , Koch Martin
Published: February 2011

We propose asymmetric D-split resonators as unit cells for high Q metasurfaces. In such resonators, current trapped modes lead to in-phase oscillations of antisymmetric currents. Thus, radiation losses are suppressed, enabling Q-factors beyond the ones obtainable in symmetric designs. We compare the proposed structure against both asymmetric and symmetric split ring metasurfaces and find an improvement in terms of Q by a factor of two and ten, respectively. Transmission measurements in a terahertz spectrometer provide experimental proof of the high Q-factors and agree well with numerical simulations. In the future, asymmetric D-split metasurfaces could be employed as high-performance sensors or filters.
A versatile microelectromechanical system for nanomechanical testing
Authors: Pant B. , Allen B. L. , Zhu T. , Gall K. , Pierron O. N.
Published: February 2011

This letter presents a microelectromechanical system (MEMS) material testing setup that relies on electronic measurements of nanospecimen elongation. Compared to previously demonstrated MEMS that rely on high magnification images to measure elongation, this MEMS is more versatile, allowing both in situ and ex situ testing of nanomaterials with high accuracy and precision. We describe and characterize the MEMS device and illustrate its mode of operation with a successful ex situ uniaxial tensile test of a nanocrystalline nickel nanobeam. The combination of ex situ and in situ nanomechanical tests will enable a thorough investigation of critical properties pertaining to the reliability of nanosystems.
Use and understanding of organic amendments in Australian agriculture: a review
Authors: Quilty J. R. , Cattle S. R.
Published: February 2011

A wide range of organic amendments (OA) is currently available to Australian farmers. These products have numerous agronomic applications, including the supply of plant nutrients, control of pests and diseases, and in management of soil health. Several of these products are also used in contaminated and degraded land remediation. The most commonly identifiable groups of OA in Australia are composts, compost teas, vermicasts, humic substances, meat, blood and bone meal, fish hydrolysates, seaweed extracts, bio-inoculants, biodynamic products, and biochars. Many of these OA contain nutrients within organic molecular structures; these nutrients are usually not immediately available to plants and must first be mineralised. Mineralisation often occurs as OA are consumed by microbes, thereby stimulating soil microbial activity. The application of OA such as bio-inoculants, humic substances, and seaweed extracts can potentially stimulate crop growth and development through the actions of plant growth-promoting hormones, including cytokinins, auxins, and gibberellins. Yet despite these apparent benefits, the widespread adoption of OA in Australia has been limited, due in part to the high application rates required to produce agronomic benefits, a lack of consistency in the composition of some products, a poor public perception of their utility, and a lack of unbiased scientific research into the agricultural potential of these products.
Comparison of three carbon determination methods on naturally occurring substrates and the implication for the quantification of 'soil carbon'
Authors: Conyers M. K. , Poile G. J. , Oates A. A. , Waters D. , Chan K. Y.
Published: February 2011

Accounting for carbon (C) in soil will require a degree of precision sufficient to permit an assessment of any trend through time. Soil can contain many chemically and physically diverse forms of organic and inorganic carbon, some of which might not meet certain definitions of ‘soil carbon’. In an attempt to assess how measurements of these diverse forms of C might vary with analytical method, we measured the C concentration of 26 substrates by three methods commonly used for soil C (Walkley–Black, Heanes, and Leco). The Heanes and Leco methods were essentially equivalent in their capture of organic C, but the Leco method captured almost all of the inorganic C (carbonates, graphite). The Heanes and Walkley–Black methods did not measure carbonates but did measure 92% and 9%, respectively, of the C in graphite. All three of the common soil test procedures measured some proportion of the charcoal and of the other burnt materials. The proportion of common organic substrates (not the carbonates, graphite, or soil) that was C by weight ranged from ~10% to 90% based on the Heanes and Leco data. The proportion of the organic fraction of those same substrates, as measured by loss-on-ignition, that was C by weight ranged from 42% to 100%. The relationship between Walkley–Black C and total C (by Heanes and Leco) showed that Walkley–Black C was a variable proportion of total C for the 26 substrates. Finally, the well-known, apparent artefact in the Cr-acid methods was investigated: dichromate digestion should contain at least 7–10 mg C in the sample or over-recovery of C might be reported. Our observation that common soil C procedures readily measure C in plant roots and shoots, and in burnt stubble, means that there will likely be intra-annual variation in soil C, because avoidance of these fresh residues is difficult. Such apparent intra-annual variation in soil C will make the detection of long-term trends problematic.
General purpose computer-assisted clustering and conceptualization
Authors: Grimmer Justin , King Gary
Published: February 2011

We develop a computer-assisted method for the discovery of insightful conceptualizations, in the form of clusterings (i.e., partitions) of input objects. Each of the numerous fully automated methods of cluster analysis proposed in statistics, computer science, and biology optimize a different objective function. Almost all are well defined, but how to determine before the fact which one, if any, will partition a given set of objects in an “insightful” or “useful” way for a given user is unknown and difficult, if not logically impossible. We develop a metric space of partitions from all existing cluster analysis methods applied to a given dataset (along with millions of other solutions we add based on combinations of existing clusterings) and enable a user to explore and interact with it and quickly reveal or prompt useful or insightful conceptualizations. In addition, although it is uncommon to do so in unsupervised learning problems, we offer and implement evaluation designs that make our computer-assisted approach vulnerable to being proven suboptimal in specific data types. We demonstrate that our approach facilitates more efficient and insightful discovery of useful information than expert human coders or many existing fully automated methods.
Climate change and other external drivers in small-scale fisheries: practical steps for responding.
Authors: Hall S. J.
Published: February 2011

The effects of international trade, market globalization, technology, climatic change, health and disease, demography, governance, development patterns and aquaculture on small-scale fisheries and practical suggestions for researchers, managers and policy makers on how to develop responses to these challenges are presented.
Gate direct-tunnelling and hot-carrier-induced hysteresis effect in partially depleted silicon-on-insulator floating-body MOSFETs
Authors: Zhou Jianhua , Pang Albert , Zou Shichang
Published: February 2011

The hysteresis effect in the output characteristics of partially depleted (PD) silicon-on-insulator (SOI) floating-body MOSFETs with an ultra-thin gate oxide is studied taking account of both gate direct-tunnelling and impact ionization-induced hot-carrier mechanisms. It is proposed that hole tunnelling from valence band (HVB) for floating-body PD SOI n-MOSFETs, electron tunnelling from conduction band (ECB) for floating-body PD SOI p-MOSFETs and impact-ionization-induced hot carriers are the main causes of the hysteresis effect. Meanwhile, body-contact structures of T-gate and H-gate PD SOI MOSFETs are also studied under floating-body configurations. It is found that the influence of the converse poly-gate on the body-contact side on gate direct-tunnelling cannot be neglected in view of floating-body potential variation. Based on the measurement results, the hysteresis can be suppressed using T-gate and H-gate PD SOI MOSFETs with floating-body configurations.