bluuebunny/crossref_metadata_2025 huggingface dataset:
1.5.1 Protic Acid/Base Induced Reactions
Authors: Adu-Ampratwum D. , Forsyth C. J.
Published: December 2017

This chapter covers synthetic domino processes that are induced by protic acid or base. They are broadly classified into those that capitalize upon the release of oxirane ring strain under acidic or basic conditions, and carbocyclic ring expansions and contractions under protic acid or basic conditions. The focus here is upon single substrate, monocomponent domino processes, rather than multicomponent variants.
1.6.5 Cobalt and Other Metal Mediated Domino Reactions: The Pauson–Khand Reaction and Its Use in Natural Product Total Synthesis
Authors: Shi L. , Yang Z.
Published: December 2017

The Pauson–Khand reaction constitutes one of the most formidable additions to the repertoire of synthetically useful reactions. It rapidly affords a cyclopentenone skeleton from an alkene, an alkyne, and carbon monoxide, based on a domino sequence of bond constructions. In this chapter, the prowess of the Pauson–Khand reaction is illustrated by judicious selection of complex target molecules, the total syntheses of which are cleverly orchestrated by the key Pauson–Khand reaction sequence. Emphasis is placed on cobalt-mediated processes to exemplify the applicability of this classical reaction.
3 Metal-Catalyzed Oxidation of Alkanes To Give Esters or Amines
Authors: Caballero A. , Díaz-Requejo M. M. , Pérez P. J.
Published: December 2017

The modification of relatively unreactive alkanes of general formula CnH2n+2, as well as of cycloalkanes CnH2n, by oxidation of C—H bonds in a catalytic manner is reviewed, focusing on their direct conversions into esters or amines upon incorporation of carbene or nitrene fragments, respectively.
5.1 Epoxidation of Alkenes
Authors: Berkessel A. , Engler H. , Leuther T. M.
Published: December 2017

The Sharpless, Jacobsen/Katsuki, and Shi epoxidations are frequently applied in the asymmetric epoxidation of relatively electron-rich alkenes. The development and application of these “classics” has been reviewed numerous times. This chapter covers recent advances in the field, e.g. with regard to the extension of asymmetric epoxidation catalysis to hitherto problematic substrate classes, such as non-conjugated terminal alkenes, or homo- and bis-homoallylic alcohols. At the same time, hydrogen peroxide continues to receive increasing attention as an environmentally friendly and economically attractive terminal oxidant. Examples of efficient organocatalytic epoxidation processes are summarized as well. For electron-poor alkenes, e.g. those carrying carbonyl, nitrile, or sulfone acceptor groups, quite remarkable progress has recently been made both in metal and organocatalysis, and the chapter also includes details of methods and protocols in this area.
5.2 Dioxygenation of Alkenes
Authors: Martínez C. , Muñiz K.
Published: December 2017

A plethora of natural products exist that contain characteristic vicinal 1,2-diols in their scaffolds. The alkene dihydroxylation methodology developed by Sharpless continues to be the most robust and general method to obtain this important motif. However, the main problem with this transformation is the use of osmium as the catalyst and, since the 1990s, various methods have been developed that employ alternative transition metals. In this chapter, the most important protocols for the racemic and enantioselective dioxygenation of alkenes mediated by metals are summarized, together with recently developed methods that employ chiral nonracemic hypervalent iodine(III) reagents.
6 Sulfinyl- and Sulfonyl-Containing Directing Groups in C—H Oxidation of Arenes
Authors: Gómez-Arrayas R. , Rodríguez N.
Published: December 2017

Although sulfur-containing directing groups, such as sulfoxides or sulfones, have only recently been employed as directing groups in C—H functionalization reactions, they have proved to be powerful tools for assisting metallacycle formation to ensure regiocontrol in a wide variety of transformations. Furthermore, the chemical versatility associated with these groups not only allows for their facile and high-yielding removal, but also provides an additional handle for the diversification of the resulting products.
8.1 Recent Developments in Catalytic Alcohol Oxidation Using Nitroxyl Radicals
Authors: Dornan L. M. , Hughes N. L. , Muldoon M. J.
Published: December 2017

This chapter describes the use of nitroxyl radicals as catalysts for the oxidation of alcohols, with a focus on recent developments in this area. Stable nitroxyl radicals can be used with a variety of different terminal oxidants and the methods discussed have a much greater substrate scope compared to precious-metal catalysts. The methods are readily accessible for small-scale applications as they use commercially available reagents and do not require high pressures or temperatures. This review not only describes the selective oxidation of alcohols to aldehydes, ketones, and carboxylic acids, but also reactions where alcohol oxidation is a key step, such as the oxidative synthesis of nitriles, imines, and amides.
10 α-Oxidation of Carbonyl Compounds
Authors: Uyanik M. , Ishihara K.
Published: December 2017

The α-heterofunctionalization of carbonyl compounds enables access to a large number of synthetic building blocks and high-value molecules. This chapter describes the direct catalytic α-oxidative coupling of carbonyl compounds with oxygen- and nitrogen-based reagents.
1.2 Partial Reduction of Polyenes
Authors: Zaccheria F. , Ravasio N.
Published: December 2017

The selective hydrogenation of polyenes represents an important transformation in organic synthesis and requires a proper design and choice of the catalyst used for C=C bond hydrogenation, as well as careful tuning of the reaction conditions. This chapter illustrates some selected examples of partial reduction of polyenes via both homogeneous and heterogeneous catalysis, including hydrogenation of terpenes, cyclic dienes, and vegetable oils, to obtain products and intermediates useful for the chemical industry.
1.9 Hydrogenation of Carbon Dioxide
Authors: Nahra F. , Cazin C. S. J.
Published: December 2017

Carbon dioxide is an economical, safe, and renewable C1 source. This attractive C1 building block is mainly used in the synthesis of organic chemicals, materials, and carbohydrates. As a feedstock to produce chemicals and fuel derivatives, carbon dioxide utilization will most certainly become an important tool in the quest for more sustainable chemistry. The atom-economical hydrogenation of carbon dioxide using dihydrogen offers a unique opportunity to achieve that goal. The main products of carbon dioxide hydrogenation or reduction fall into two categories: fuels and chemicals. The main topics discussed in this chapter are the hydrogenation of carbon dioxide to formic acid, methanol, and methane, as well as the reductive methylation of amines and C—H bonds. Both homogeneous and heterogeneous catalytic metal systems are reviewed herein.
1.8 Catalytic Reduction of Carbonates
Authors: Li Y. , Ding K.
Published: December 2017

Carbonates are basic chemicals that are widely used in both industry and academia. Their reduction under either homogeneous or heterogeneous catalytic conditions generates formates, methanol, or methane. Carbonates can also act as a C1 building block for the reductive methylation of amines.
1.10 Reduction of Peroxo Compounds, Ozonides, and Molozonides
Authors: Poechlauer P. , Zimmermann A.
Published: December 2017

Research in the field of heterogeneous catalytic hydrogenation of peroxo compounds, ozonides, and molozonides has delivered results in a diverse range of fields of organic chemistry. It has revealed details of the reaction mechanisms that take place at the catalyst surface, and has enabled further understanding of the factors governing the chemoselectivity of various catalysts. Apart from enabling yield increases in single transformations, this has also opened up opportunities to apply the introduction and subsequent hydrogenation of peroxo moieties in multistep syntheses of complex molecules. The facile introduction of the peroxide moiety via very different reactions at positions otherwise difficult to access, and its subsequent transformation in the presence of other functional groups, has allowed the design of concise synthetic pathways to complex molecules, including pharmaceuticals and natural products.
Enhanced hot-electron production and strong-shock generation in hydrogen-rich ablators for shock ignition
Authors: Theobald W. , Bose A. , Yan R. , Betti R. , Lafon M. , Mangino D. , Christopherson A. R. , Stoeckl C. , Seka W. , Shang W. , Michel D. T. , Ren C. , Nora R. C. , Casner A. , Peebles J. , Beg F. N. , Ribeyre X. , Llor Aisa E. , Colaïtis A. , Tikhonchuk V. , Wei M. S.
Published: December 2017

Experiments were performed with CH, Be, C, and SiO2 ablators interacting with high-intensity UV laser radiation (5 × 1015 W/cm2, λ = 351 nm) to determine the optimum material for hot-electron production and strong-shock generation. Significantly more hot electrons are produced in CH (up to ∼13% instantaneous conversion efficiency), while the amount is a factor of ∼2 to 3 lower in the other ablators. A larger hot-electron fraction is correlated with a higher effective ablation pressure. The higher conversion efficiency in CH is attributed to stronger damping of ion-acoustic waves because of the presence of light H ions.
High-Mach number, laser-driven magnetized collisionless shocks
Authors: Schaeffer D. B. , Fox W. , Haberberger D. , Fiksel G. , Bhattacharjee A. , Barnak D. H. , Hu S. X. , Germaschewski K. , Follett R. K.
Published: December 2017

Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide a complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and a magnetized ambient plasma. Through time-resolved, 2-D imaging, we observe large density and magnetic compressions that propagate at super-Alfvénic speeds and that occur over ion kinetic length scales. The electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. The simulations also show the shock separating from the piston, which we observe in the data at late experimental times.
Microstructures and dynamics of tetraalkylphosphonium chloride ionic liquids
Authors: Wang Yong-Lei , Li Bin , Sarman Sten , Laaksonen Aatto
Published: December 2017

Atomistic simulations have been performed to investigate the effect of aliphatic chain length in tetraalkylphosphonium cations on liquid morphologies, microscopic ionic structures, and dynamical quantities of tetraalkylphosphonium chloride ionic liquids. The liquid morphologies are characterized by sponge-like interpenetrating polar and apolar networks in ionic liquids consisting of tetraalkylphosphonium cations with short aliphatic chains. The lengthening aliphatic chains in tetraalkylphosphonium cations lead to polar domains consisting of chloride anions and central polar groups in cations being partially or totally segregated in ionic liquid matrices due to a progressive expansion of apolar domains in between. Prominent polarity alternation peaks and adjacency correlation peaks are observed at low and high q range in total X-ray scattering structural functions, respectively, and their peak positions gradually shift to lower q values with lengthening aliphatic chains in tetraalkylphosphonium cations. The charge alternation peaks registered in the intermediate q range exhibit complicated tendencies due to a cancellation of peaks and anti-peaks in partial structural functions for ionic subcomponents. The particular microstructures and liquid morphologies in tetraalkylphosphonium chloride ionic liquids intrinsically contribute to distinct dynamics characterized by mean square displacements, van Hove correlation functions, and non-Gaussian parameters for ionic species in the heterogeneous ionic environment. Most tetraalkylphosphonium cations have higher translational mobilities than their partner anions due to strong coordination of chloride anions with central polar groups in tetraalkylphosphonium cations through strong Coulombic and hydrogen bonding interactions. The increase of aliphatic chain length in tetraalkylphosphonium cations leads to a concomitant shift of van Hove correlation functions and non-Gaussian parameters to larger radial distances and longer time scales, respectively, indicating the enhanced translational dynamical heterogeneities of tetraalkylphosphonium cations and the corresponding chloride anions.
Cholesteric and screw-like nematic phases in systems of helical particles
Authors: Cinacchi Giorgio , Ferrarini Alberta , Giacometti Achille , Kolli Hima Bindu
Published: December 2017

Recent numerical simulations of hard helical particle systems unveiled the existence of a novel chiral nematic phase, termed screw-like, characterised by the helical organization of the particle C2 symmetry axes round the nematic director with periodicity equal to the particle pitch. This phase forms at high density and can follow a less dense uniform nematic phase, with relative occurrence of the two phases depending on the helix morphology. Since these numerical simulations were conducted under three-dimensional periodic boundary conditions, two questions could remain open. First, the real nature of the lower density nematic phase, expected to be cholesteric. Second, the influence that the latter, once allowed to form, may have on the existence and stability of the screw-like nematic phase. To address these questions, we have performed Monte Carlo and molecular dynamics numerical simulations of helical particle systems confined between two parallel repulsive walls. We have found that the removal of the periodicity constraint along one direction allows a relatively-long-pitch cholesteric phase to form, in lieu of the uniform nematic phase, with helical axis perpendicular to the walls while the existence and stability of the screw-like nematic phase are not appreciably affected by this change of boundary conditions.
Two dimensional radial gas flows in atmospheric pressure plasma-enhanced chemical vapor deposition
Authors: Kim Gwihyun , Park Seran , Shin Hyunsu , Song Seungho , Oh Hoon-Jung , Ko Dae Hong , Choi Jung-Il , Baik Seung Jae
Published: December 2017

Atmospheric pressure (AP) operation of plasma-enhanced chemical vapor deposition (PECVD) is one of promising concepts for high quality and low cost processing. Atmospheric plasma discharge requires narrow gap configuration, which causes an inherent feature of AP PECVD. Two dimensional radial gas flows in AP PECVD induces radial variation of mass-transport and that of substrate temperature. The opposite trend of these variations would be the key consideration in the development of uniform deposition process. Another inherent feature of AP PECVD is confined plasma discharge, from which volume power density concept is derived as a key parameter for the control of deposition rate. We investigated deposition rate as a function of volume power density, gas flux, source gas partial pressure, hydrogen partial pressure, plasma source frequency, and substrate temperature; and derived a design guideline of deposition tool and process development in terms of deposition rate and uniformity.
The influence of Sb content and dots size of InAs/GaAs(1-x)Sbx quantum dot on type I-type II band alignment and carrier dynamics
Authors: Li Yaqian , Ji Lian , Lu Shulong , Ding Chao , Zhou Jianqiu
Published: December 2017

The band structure and carrier dynamics of InAs/GaAs(1-x)Sbx/GaAs quantum dots (QDs) are investigated by the eight-band model and by looking at the optical matrix elements of the envelope functions. Simulation solutions were obtained for different Sb concentrations in the cover layer and different QD heights. The results indicated that the conversion process from type I to type II caused by the Sb content could be divided into three stages: type I (less than 8%), the turning process (8%–14%), and type II (more than 14%). The influence of QD height on the wave function of carriers can be seen only in the second stage. It reverses the effect of Sb content by influencing the quantum confinement of hole states. Additionally, the potential radiation recombination channels are changed by these two factors. Unlike the first stage (where the ground-state transition is mainly channel), the first two hole levels and the first two electron levels are involved in radiation recombination in the second stage. So two recombination channels could be observed in the latter part of the second stage, which is consistent with the experimental results from the literature.
Stability of horizontal viscous fluid layers in a vertical arbitrary time periodic electric field
Authors: Bandopadhyay Aditya , Hardt Steffen
Published: December 2017

The stability of a horizontal interface between two viscous fluids, one of which is conducting and the other is dielectric, acted upon by a vertical time-periodic electric field is considered theoretically. The two fluids are bounded by electrodes separated by a finite distance. For an applied ac electric field, the unstable interface deforms in a time periodic manner, owing to the time dependent Maxwell stress, and is characterized by the oscillation frequency which may or may not be the same as the frequency of the ac electric field. The stability curve, which relates the critical voltage, manifested through the Mason number—the ratio of normal electric stress and viscous stress, and the instability wavenumber at the onset of the instability, is obtained by means of the Floquet theory for a general arbitrary time periodic electric field. The limit of vanishing viscosities is shown to be in excellent agreement with the marginal stability curves predicted by means of a Mathieu equation. The influence of finite viscosity and electrode separation is discussed in relation to the ideal case of inviscid fluids. The methodology to obtain the marginal stability curves developed here is applicable to any arbitrary but time periodic signal, as demonstrated for the case of a signal with two different frequencies, and four different frequencies with a dc offset. The mode coupling in the interfacial normal stress leads to appearance of harmonic and subharmonic modes, characterized by the frequency of the oscillating interface at an integral or half-integral multiple of the applied frequency, respectively. This is in contrast to the application of a voltage with a single frequency which always leads to a harmonic mode oscillation of the interface. Whether a harmonic or subharmonic mode is the most unstable one depends on details of the excitation signal.
Lasing at 602-620 nm from a red algae-derived phycobiliprotein
Authors: Rivera José A. , Eden J. Gary
Published: December 2017

Lasing in the 602-620 nm (orange-red) spectral region has been observed from R-phycoerythrin (RPE), a phycobiliprotein responsible for the >80% quantum yield of red algae. Photoexcitation of 8 μM RPE solutions in a Fabry-Pérot resonator with frequency-doubled Nd:YAG laser pulses (λp = 532 nm) yields >26 nJ of energy in ∼2.5 ns (FWHM) pulses, which corresponds to >10 W of peak power. Maximum laser emission occurs at ∼610 nm, the threshold pump energy fluence is measured to be 260 ± 15 μJ/mm2, and more than 100 longitudinal laser modes are generated when the cavity free spectral range and mirror separation are Δλ = 0.18 nm and L = 777 ± 1 μm, respectively. In combination with the known versatility of the phycobiliproteins as fluorescent tags, the biomolecular RPE laser reported here suggests its applicability to clinical assays and in situ laser imaging.
Harvesting energy from Faraday waves
Authors: Alazemi Saad , Lacarbonara Walter , Daqaq Mohammed F.
Published: December 2017

Since their discovery in 1831, Faraday waves have played a crucial role in the development of novel methodologies for vibration absorption or assembly of microscale materials including soft matter and biological constituents. This work discusses a fundamentally different application of Faraday waves. A new methodology is proposed to harness energy from environmental vibrations via the activation of Faraday waves on the surface of a magnetic fluid. To this end, a proof-of-concept of the proposed harvester is first presented and its performance is experimentally analyzed near the principal parametric resonances of the first and second modes. Subsequently, a mathematical model is constructed to describe the dynamic behavior of the harvester using perturbation techniques. The model is validated against experimental data and light is shed onto the favorable conditions for energy harvesting.
Dual scan CT image recovery from truncated projections
Authors: Sarkar Shubhabrata , Wahi Pankaj , Munshi Prabhat
Published: December 2017

There are computerized tomography (CT) scanners available commercially for imaging small objects and they are often categorized as mini-CT X-ray machines. One major limitation of these machines is their inability to scan large objects with good image quality because of the truncation of projection data. An algorithm is proposed in this work which enables such machines to scan large objects while maintaining the quality of the recovered image.
Shock wave propagation and spall failure of nanocrystalline Cu/Ta alloys: Effect of Ta in solid-solution
Authors: Chen Jie , Tschopp Mark A. , Dongare Avinash M.
Published: December 2017

The role of the concentration and distribution of the Ta solute in a solid solution in the shock response and spall failure of a bulk nanocrystalline Cu (nc-Cu) system is investigated using large scale molecular dynamics (MD) simulations. The nanocrystalline Cu/Ta (nc-Cu/Ta) microstructures comprise a 16 nm grain size Cu matrix with distributions of 3.0%, 6.3%, and 10.0% Ta atoms either along the grain boundary or randomly in the Cu matrix. The shock response is investigated by identifying the modifications in the dynamic evolution of defect structures (dislocation nucleation and interactions), as well as the nucleation and evolution of voids. The MD simulations reveal the complex role of Ta in altering the spall behavior of the nc-Cu system. The presence of Ta is observed to improve the spall strengths of the nc-Cu system, and the strengthening behavior is achieved by limiting the capability to nucleate dislocations during shock compression and under tensile pressures. The highest values for spall strength are observed for a random distribution of Ta at a concentration of 6.3% Ta. While the increase in strength for a 16 nm grain sized nc-Cu system is reported to be ∼8%, the role of the Ta solute is observed to be more pronounced at a larger grain size of 30 nm with a ∼15% increase in the spall strength for randomly distributed Ta with a concentration of 6.3%. The links between the concentration and the distribution of Ta in the solid solution and the evolution of microstructures under shock loading conditions are discussed.
Adiabatic perturbation theory for atoms and molecules in the low-frequency regime
Authors: Martiskainen Hanna , Moiseyev Nimrod
Published: December 2017

There is an increasing interest in the photoinduced dynamics in the low frequency, ω, regime. The multiphoton absorptions by molecules in strong laser fields depend on the polarization of the laser and on the molecular structure. The unique properties of the interaction of atoms and molecules with lasers in the low-frequency regime imply new concepts and directions in strong-field light-matter interactions. Here we represent a perturbational approach for the calculations of the quasi-energy spectrum in the low-frequency regime, which avoids the construction of the Floquet operator with extremely large number of Floquet channels. The zero-order Hamiltonian in our perturbational approach is the adiabatic Hamiltonian where the atoms/molecules are exposed to a dc electric field rather than to ac-field. This is in the spirit of the first step in the Corkum three-step model. The second-order perturbation correction terms are obtained when iℏω∂∂τ serves as a perturbation and τ is a dimensionless variable. The second-order adiabatic perturbation scheme is found to be an excellent approach for calculating the ac-field Floquet solutions in our test case studies of a simple one-dimensional time-periodic model Hamiltonian. It is straightforward to implement the perturbation approach presented here for calculating atomic and molecular energy shifts (positions) due to the interaction with low-frequency ac-fields using high-level electronic structure methods. This is enabled since standard quantum chemistry packages allow the calculations of atomic and molecular energy shifts due to the interaction with dc-fields. In addition to the shift of the energy positions, the energy widths (inverse lifetimes) can be obtained at the same level of theory. These energy shifts are functions of the laser parameters (low frequency, intensity, and polarization).
Terahertz electromagnetic radiation based on the interaction between a self-modulated electron beam and plasma wakefield
Authors: Yang Shengpeng , Zhou Qing , Tang Changjian , Chen Shaoyong
Published: December 2017

This particle-in-cell simulation study finds that the system of a long relativistic electron beam passing through an overdense plasma can produce high harmonic terahertz electromagnetic radiation. In this process, the electron beam is self-modulated to create a periodic electromagnetic structure which will resonate with the plasma wakefield and excite the electromagnetic instability in the nonlinear stage of the self-modulation. The study also finds that when the radiation is achieved, the self-modulated electron beam will be destroyed due to the self-consistent interaction among the radiation, the electron beam, and the plasma. Meanwhile, the radiation will gradually attenuate, which also coincides with the physical explanation of the radiation.
Nonlinear dielectric features of highly polar glass formers: Derivatives of propylene carbonate
Authors: Young-Gonzales A. R. , Adrjanowicz K. , Paluch M. , Richert R.
Published: December 2017

We have measured the nonlinear dielectric behavior of several highly polar propylene carbonate (PC) derivatives in the vicinity of their glass transition temperatures. Focus is on the effects of a large static electric field on the frequency dependent permittivity and on the cubic susceptibility measured using sinusoidal fields of high amplitude. The case of vinyl-PC shows dielectric saturation as well as an electro-rheological effect, i.e., a field induced increase of dielectric relaxation times, whose magnitude changes linearly with the apparent activation energy. The extent of this shift of the loss profile caused by the field correlates strongly with the peak magnitude of the cubic susceptibility, |χ3|, underlining the notion of a link between the |χ3| “hump” and this electro-rheological behavior. Further support for this picture emerges from the observation that the most polar of these liquids, (S)-(−)-methoxy-PC with εs ≈ 250, lacks both the electro-rheological effect in ε″(ω) and the “hump” typically observed in |χ3(ω)|. The absence of any sensitivity of the dynamics to an electric field is contrary to the expectation that the electro-rheological effect correlates with the field induced entropy change, which is extraordinarily high for this liquid. The results suggest that the dependence of the relaxation time on the electric field is not directly linked to the entropy change.
Quantum control of coherent π-electron ring currents in polycyclic aromatic hydrocarbons
Authors: Mineo Hirobumi , Fujimura Yuichi
Published: December 2017

We present results for quantum optimal control (QOC) of the coherent π electron ring currents in polycyclic aromatic hydrocarbons (PAHs). Since PAHs consist of a number of condensed benzene rings, in principle, there exist various coherent ring patterns. These include the ring current localized to a designated benzene ring, the perimeter ring current that flows along the edge of the PAH, and the middle ring current of PAHs having an odd number of benzene rings such as anthracene. In the present QOC treatment, the best target wavefunction for generation of the ring current through a designated path is determined by a Lagrange multiplier method. The target function is integrated into the ordinary QOC theory. To demonstrate the applicability of the QOC procedure, we took naphthalene and anthracene as the simplest examples of linear PAHs. The mechanisms of ring current generation were clarified by analyzing the temporal evolutions of the electronic excited states after coherent excitation by UV pulses or (UV+IR) pulses as well as those of electric fields of the optimal laser pulses. Time-dependent simulations of the perimeter ring current and middle ring current of anthracene, which are induced by analytical electric fields of UV pulsed lasers, were performed to reproduce the QOC results.
Self-organized criticality in a cold plasma
Authors: Alex Prince , Carreras Benjamin Andres , Arumugam Saravanan , Sinha Suraj Kumar
Published: December 2017

We present direct evidence for the existence of self-organized critical behavior in cold plasma. A multiple anodic double layer structure generated in a double discharge plasma setup shows critical behavior for the anode bias above a threshold value. Analysis of the floating potential fluctuations reveals the existence of long-range time correlations and power law behavior in the tail of the probability distribution function of the fluctuations. The measured Hurst exponent and the power law tail in the rank function are strong indication of the self-organized critical behavior of the system and hence provide a condition under which complexities arise in cold plasma.
Native seed for restoration: a discussion of key issues using examples from the flora of southern Australia
Authors: Broadhurst Linda , Waters Cathy , Coates David
Published: December 2017

Land clearing across southern Australia since European settlement has fundamentally changed the amount and distribution of native vegetation; it has also substantially reduced genetic diversity in plant species throughout Australia, especially in agricultural regions. The most recent State of the Environment report indicates that Australian biodiversity continues to decline. Many approaches to restoration are used in Australia including re-establishing plant populations using tube stock or by direct seeding. Native seed for these projects is often assumed to be plentiful and available for the majority of species we wish to restore but these assumptions are rarely true. We also rely on a small number of species for the majority of restoration projects despite the vast number of species required to fully restore complex plant communities. The majority of seed for restoration is still primarily collected from native vegetation despite longstanding concerns regarding the sustainability of this practice and the globally recognised impacts of vegetation fragmentation on seed production and genetic diversity. Climate change is also expected to challenge seed production as temperatures rise and water availability becomes more limited; changes to current planting practices may also be required. Until now native seed collection has relied on market forces to build a strong and efficient industry sector, but in reality the Australian native seed market is primarily driven by Federal, State and Territory funding. In addition, unlike other seed-based agri-businesses native seed collection lacks national industry standards. A new approach is required to support development of the native seed collection and use sector into an innovative industry.
The ethics of robotic caregivers
Authors: Etzioni Amitai , Etzioni Oren
Published: December 2017

As Artificial Intelligence technology seems poised for a major take-off and changing societal dynamics are creating a high demand for caregivers for elders, children, and those infirmed, robotic caregivers may well be used much more often. This article examines the ethical concerns raised by the use of AI caregivers and concludes that many of these concerns are avoided when AI caregivers operate as partners rather than substitutes. Furthermore, most of the remaining concerns are minor and are faced by human caregivers as well. Nonetheless, because AI caregivers’ systems are learning systems, an AI caregiver could stray from its initial guidelines. Therefore, subjecting AI caregivers to an AI-based oversight system is proposed to ensure that their actions remain both legal and ethical.
The expression of mirativity through aspectual constructions
Authors: De Wit Astrid
Published: December 2017

While some languages appear to have dedicated mirative constructions, others convey mirative meanings through originally “non-mirative categories which acquire mirative meanings in a given context” (Aikhenvald, 2012, p. 462). Such mirative extensions of existing constructions have been observed and analyzed at length for evidentials, yet this paper demonstrates that mirative meanings can also be conveyed through certain aspectual constructions, specifically those that select event verbs. A detailed discussion of various aspectual constructions in diverging languages shows that progressive, perfect and perfective aspect markers often prompt mirative interpretations of surprise, novelty or incongruity. I claim that these mirative features are a consequence of the intrinsic association of these aspectual constructions with event verbs and the ‘phenomenal’ situations they refer to, i.e., situations that are susceptible to change. Such phenomenal situations lend themselves more naturally to mirative readings, as their occurrence and development at a certain point in time cannot be fully predicted.
Originalidad léxica del español americano
Authors: Cáceres-Lorenzo M. Teresa
Published: December 2017

Abstracto

La originalidad del localismo dialectal en los diccionarios proporciona información sobre la selección léxica de las distintas comunidades de hispanohablantes. En este estudio se ha diseñado una investigación para medir el grado de originalidad léxica en América, según las marcas diatópicas que aparecen en elDiccionario de Americanismos(DA). Las variables analizadas que inciden sobre la originalidad, son el número total de términos, lexías exclusivas, número de hispanohablantes y esfuerzo recolector. El material seleccionado ha sido la ictionimia vernácula registrada en elDA. Nuestra indagación, de naturaleza cuantitativa, nos ofrece evidentes diferencias entre regiones, como es el alto índice de originalidad de Puerto Rico frente al de Uruguay. Las conclusiones que aportamos quieren ser una contribución a la definición y clasificación del dialectalismo desde el análisis diatópico.
La Suède, un modèle littéraire en voie d’autonomie ?
Authors: Cedegren Mickaëlle , Lindberg Ylva
Published: December 2017

This study offers an in-depth analysis of the reception in the Swedish daily press (2010–2014) of three Francophone authors: Crowther, Taïa, and Thúy. Through a new approach combining concepts like consecrational transfers (Casanova), cultural transfer (Espagne), and ideologic functions (Moura), the analysis reveals Sweden’s efforts to become a consecrating pole. Firstly, while stressing the “difference” as a principal feature of the commented literature, Sweden tries to foreground its own national project to jointly promote diversity, migrancy and cohesion. Secondly, comparing the Francophone literature with its own, Swedish critics manage to consecrate literature from another dominated country. Finally, comparisons with more international references leave space for self-consecration and access to a more dominant position on the market. Thus, the transmitted literature is less at stake than the receiving country’s own image.
IL-33 promotes the egress of group 2 innate lymphoid cells from the bone marrow
Authors: Stier Matthew T. , Zhang Jian , Goleniewska Kasia , Cephus Jacqueline Y. , Rusznak Mark , Wu Lan , Van Kaer Luc , Zhou Baohua , Newcomb Dawn C. , Peebles R. Stokes
Published: December 2017

Group 2 innate lymphoid cells (ILC2s) are effector cells within the mucosa and key participants in type 2 immune responses in the context of allergic inflammation and infection. ILC2s develop in the bone marrow from common lymphoid progenitor cells, but little is known about how ILC2s egress from the bone marrow for hematogenous trafficking. In this study, we identified a critical role for IL-33, a hallmark peripheral ILC2-activating cytokine, in promoting the egress of ILC2 lineage cells from the bone marrow. Mice lacking IL-33 signaling had normal development of ILC2s but retained significantly more ILC2 progenitors in the bone marrow via augmented expression of CXCR4. Intravenous injection of IL-33 or pulmonary fungal allergen challenge mobilized ILC2 progenitors to exit the bone marrow. Finally, IL-33 enhanced ILC2 trafficking to the lungs in a parabiosis mouse model of tissue disruption and repopulation. Collectively, these data demonstrate that IL-33 plays a critical role in promoting ILC2 egress from the bone marrow.
Stargazin and cornichon-3 relieve polyamine block of AMPA receptors by enhancing blocker permeation
Authors: Brown Patricia M.G.E. , McGuire Hugo , Bowie Derek
Published: December 2017

Most ligand- and voltage-gated ion channels assemble as signaling complexes consisting of pore-forming and auxiliary subunits. In the mammalian brain, AMPA-type ionotropic glutamate receptors (AMPARs) coassemble with several families of auxiliary subunits that regulate channel gating as well as ion channel block and permeation. Previous work has shown that auxiliary proteins stargazin (or γ2) and cornichon-3 (CNIH-3) attenuate the cytoplasmic polyamine channel block of AMPARs, although the underlying mechanism has yet to be established. Here, we show that γ2 and CNIH-3 relieve channel block by enhancing the rate of blocker permeation. Surprisingly, the relative permeability of the polyamine spermine (Spm) through the pore of the AMPAR-γ2 or -CNIH-3 complexes is considerably more than AMPARs expressed alone. Spm permeability is comparable to that of Na+ for the GluA2-γ2 complex and four times greater than Na+ with GluA2 + CNIH-3. A modified model of permeant channel block fully accounts for both the voltage- and time-dependent nature of Spm block. Estimates of block rate constants reveal that auxiliary subunits do not attenuate block by shifting the location of the block site within the membrane electric field, and they do not affect the blocker’s ability to reach it. Instead, γ2 and CNIH-3 relieve channel block by facilitating the blocker’s exit rates from the open channel. From a physiological perspective, the relief of channel block exerted by γ2 and CNIH-3 ensures that there is unfettered signaling by AMPARs at glutamatergic synapses. Moreover, the pronounced ability of AMPARs to transport polyamines may have an unexpected role in regulating cellular polyamine levels.
Reflections on Agricultural R&D, Productivity, and the Data Constraint: Unfinished Business, Unsettled Issues
Authors: Alston Julian M
Published: December 2017

Sixty years ago, T.W. Schultz introduced the idea of the productivity “residual” to agricultural economics (1956). Schultz's main message was that growth in conventional inputs accounted for little of the observed growth in agricultural output, and that there was work to be done by agricultural economists to understand and ultimately eliminate this unexplained residual called “productivity.” Thus was launched the economics of agricultural productivity as a sub‐field within agricultural economics, along with the economics of agricultural R&D and innovation and related government policy. Much progress has been made in the decades since. Still, critical issues remain unresolved. This matters because agricultural innovation and productivity matter, and so do the related policies that rest to some extent on our established understanding of the economic relationships. In this paper I review some unsettled issues related to economic models and measures applied to agricultural R&D and productivity, and some unfinished business in terms of economic and policy questions that are not yet well answered. Before doing that, I present some evidence on agricultural productivity and why it matters. Next, with a nod to “factology,” I present available productivity measures from the U.S. Department of Agriculture (USDA) and International Science and Technology Practice and Policy (InSTePP) Center, and compare them in the context of translog cost function models. In subsequent sections I use these and other data to develop new evidence related to two contentious questions: (a) Do farmers benefit from public agricultural R&D? (b) Has U.S. agricultural productivity growth slowed in recent decades? The answers are revealed within.
Role of yes-associated protein 1, angiomotin, and mitogen-activated kinase kinase 1/2 in development of the bovine blastocyst†
Authors: Negrón-Pérez Verónica M , Hansen Peter J
Published: December 2017

The morula-stage embryo is transformed into a blastocyst composed of epiblast, hypoblast, and trophectoderm (TE) through mechanisms that, in the mouse, involve the Hippo signaling and mitogen-activated kinase (MAPK) pathways. Using the cow as an additional model, we tested the hypotheses that TE and hypoblast differentiation were regulated by the Hippo pathway regulators, yes-associated protein 1 (YAP1) and angiomotin (AMOT), and MAPK kinase 1/2 (MAPK1/2). The presence of YAP1 and CDX2 in the nucleus and cytoplasm of MII oocytes and embryos was evaluated by immunofluorescence labeling. For both molecules, localization changed from cytoplasmic to nuclear as development advanced. Inhibition of YAP1 activity, either by verteporfin or a YAP1 targeting GapmeR, reduced the percent of zygotes that became blastocysts, the proportion of blastocysts that hatched and numbers of CDX2+ cells in blastocysts. Moreover, the YAP1-targeting GapmeR altered expression of 15 of 91 genes examined in the day 7.5 blastocyst. Treatment of embryos with an AMOT targeting GapmeR did not affect blastocyst development or hatching but altered expression of 16 of 91 genes examined at day 7.5 and reduced the number of CDX2+ nuclei and YAP1+ nuclei in blastocysts at day 8.5 of development. Inhibition of MAPK1/2 with PD0325901 did not affect blastocyst development but increased the number of epiblast cells. Results indicate a role for YAP1 and AMOT in function of TE in the bovine blastocyst. YAP1 can also affect function of the epiblast and hypoblast, and MAPK signaling is important for inner cell mass differentiation by reducing epiblast numbers.
The intriguing evolution of effect sizes in biomedical research over time: smaller but more often statistically significant
Authors: Monsarrat Paul , Vergnes Jean-Noel
Published: December 2017

Background

In medicine, effect sizes (ESs) allow the effects of independent variables (including risk/protective factors or treatment interventions) on dependent variables (e.g., health outcomes) to be quantified. Given that many public health decisions and health care policies are based on ES estimates, it is important to assess how ESs are used in the biomedical literature and to investigate potential trends in their reporting over time.

Results

Through a big data approach, the text mining process automatically extracted 814 120 ESs from 13 322 754 PubMed abstracts. Eligible ESs were risk ratio, odds ratio, and hazard ratio, along with their confidence intervals. Here we show a remarkable decrease of ES values in PubMed abstracts between 1990 and 2015 while, concomitantly, results become more often statistically significant. Medians of ES values have decreased over time for both “risk” and “protective” values. This trend was found in nearly all fields of biomedical research, with the most marked downward tendency in genetics. Over the same period, the proportion of statistically significant ESs increased regularly: among the abstracts with at least 1 ES, 74% were statistically significant in 1990–1995, vs 85% in 2010–2015.

Conclusions

whereas decreasing ESs could be an intrinsic evolution in biomedical research, the concomitant increase of statistically significant results is more intriguing. Although it is likely that growing sample sizes in biomedical research could explain these results, another explanation may lie in the “publish or perish” context of scientific research, with the probability of a growing orientation toward sensationalism in research reports. Important provisions must be made to improve the credibility of biomedical research and limit waste of resources.
When Being in a Positive Mood Increases Choice Deferral
Authors: Etkin Jordan , Ghosh Anastasiya Pocheptsova
Published: December 2017

Consumers’ choices are often accompanied by unrelated incidental moods. The positive mood caused by receiving a compliment, for example, may persist when one is choosing what service to book or which product to buy. How might being in a positive mood affect consumers’ subsequent, unrelated choices? The present research demonstrates that being in a positive mood can make consumers more likely to defer choice. Four studies show that when choosing requires trade-offs between important choice attributes, being in a positive (vs. neutral) mood makes choosing more difficult and therefore increases the likelihood of deferring choice altogether. The findings further understanding of how incidental factors shape choice processes and outcomes and the role of emotions in decision making.