bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanowires and Nanostructures that Grow like Polymer Molecules
Authors: Shaw Santosh , Cademartiri Ludovico
Published: June 2013

Unique properties (e.g., rubber elasticity, viscoelasticity, folding, reptation) determine the utility of polymer molecules and derive from their morphology (i.e., one‐dimensional connectivity and large aspect ratios) and flexibility. Crystals do not display similar properties because they have smaller aspect ratios, they are rigid, and they are often too large and heavy to be colloidally stable. We argue, with the support of recent experimental studies, that these limitations are not fundamental and that they might be overcome by growth processes that mimic polymerization. Furthermore, we (i) discuss the similarities between crystallization and polymerization, (ii) critically review the existing experimental evidence of polymer‐like growth kinetic and behavior in crystals and nanostructures, and (iii) propose heuristic guidelines for the synthesis of “polymer‐like” crystals and assemblies. Understanding these anisotropic materials at the boundary between molecules and solids will determine whether we can confer the unique properties of polymer molecules to crystals, expanding them with topology, dynamics, and information and not just tuning them with size.
Association of epidermal growth factor receptor mutations with human papillomavirus 16/18 E6 oncoprotein expression in non–small cell lung cancer
Authors: Tung Min‐Che , Wu Heng‐Hsiung , Cheng Ya‐Wen , Wang Lee , Chen Chih‐Yi , Yeh Sauh‐Der , Wu Tzu‐Chin , Lee Huei
Published: June 2013

BACKGROUND

Lung cancers in women, in nonsmokers, and in patients with adenocarcinoma from Asia have more prevalent mutations in the epidermal growth factor receptor (EGFR) gene than their counterparts. However, the etiology of EGFR mutations in this population remains unclear. The authors hypothesized that the human papillomavirus (HPV) type 16/18 (HPV16/18) E6 oncoprotein may contribute to EGFR mutations in Taiwanese patients with lung cancer.

METHODS

One hundred fifty‐one tumors from patients with lung cancer were enrolled to determine HPV16/18 E6 and EGFR mutations using immunohistochemistry and direct sequencing, respectively. Levels of 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxo‐dG) in lung tumors and cells were evaluated using immunohistochemistry and liquid chromatography‐mass spectrometry/mass spectrometry. An supF mutagenesis assay was used to determine H2O2‐induced mutation rates of lung cancer cells with or without E6 expression.

RESULTS

Patients with E6‐positive tumors had a greater frequency of EGFR mutations than those with E6‐negative tumors (41% vs 20%; P = .006). Levels of 8‐oxo‐dG were correlated with EGFR mutations (36% vs 16%; P = .012). Two stable clones of E6‐overexpressing H157 and CL‐3 cells were established for the supF mutagenesis assay. The data indicated that the cells with high E6 overexpression had higher H2O2‐induced SupF gene mutation rates compared with the cells that expressed lower levels of E6 and compared with vector control cells.

CONCLUSIONS

HPV16/18 E6 may contribute in part to EGFR mutations in lung cancer, at least in the Taiwanese population. Cancer 2013;119:3367–76. © 2013 American Cancer Society.
Adolescent Identity Development and Distress in a Clinical Sample
Authors: Wiley Rachel E. , Berman Steven L.
Published: June 2013

Objective

The purpose of this study was to examine the relationships of identity development and identity distress to psychological adjustment within adolescents affected by psychological problems.

Method

Participants included 88 adolescents (43.2% female) ranging from 11 to 20 years of age who were receiving services from a community mental health center.

Results

A high proportion of the participants (22.7%) met the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition Text Revision criteria for Identity Problem. Regression analyses found psychopathology symptom score was associated with identity distress, identity exploration, and identity commitment, while identity distress was only related to psychopathology symptom score and not the other two identity variables.

Conclusions

Adolescents with a clinical diagnosis may report significant levels of identity distress. Given that the relationship between psychopathology and identity distress may be reciprocal, assessing for identity issues might be prudent when conducting clinical diagnostic interviews and useful in treatment planning.
Field‐aligned current loop model on formation of sporadic metal layers
Authors: Matuura Nobuo , Tsuda Takuo , Nozawa Satonori
Published: June 2013

This paper proposes a new mechanism for the formation of the sporadic layers by metallic ions as well as metallic atoms in the lower thermosphere and upper mesosphere. The mechanism is based on sporadic occurrence of an electric current loop consisting of the magnetic field‐aligned current (FAC) and horizontal Pedersen current in the ionosphere connected with the FAC. The essential point of the present mechanism is the existence of the horizontal electric field convergence at the foot of the upward FAC region in the current loop, where the positive ions including the metallic ions may converge by the horizontal Pedersen flow. The accumulated metallic ions are reacted to the clustered metallic ions, which are transferred to the metallic atoms through the dissociative recombination with electrons. The density profile of the sporadic layer for metallic ions has been obtained in the analytical form by solving the continuity equation. The density profile of the sporadic layer for metallic atoms has been obtained also in the analytical form by assuming that 100% of the loss of the metallic ions is converted to metallic atoms. The simulation based on the present mechanism has been examined with respect to three species of metallic components: sodium, iron, and calcium. The sporadic sodium layer (SSL) derived from the present model is compared with the SSL observed by the sodium lidar installed at the European Incoherent Scatter radar site in Tromsø (69.6°N, 19.2°E), Norway, and reasonable agreement has been attained with respect to the density profile of the SSL.
Modeling the Semicontinuous Heterophase Polymerization for Synthesizing Poly(n‐butyl methacrylate) Nanoparticles
Authors: Pérez‐García María G. , Pérez‐Carrillo Lourdes A. , Mendizábal Eduardo , Puig Jorge E. , López‐Serrano Francisco
Published: June 2013

A simple four‐state model containing five‐parameters, in conjunction with experimental conversion, particle number density and average molar masses, is presented to reproduce the semicontinuous heterophase polymerization of butyl methacrylate. The model adequately describes the experimental evolutions of conversion, particle size, average number of particles, average number of radicals per particle, and molar mass. A coagulation mechanism was detected and its rate constant was evaluated. The entry coefficient and the critical radical concentration in the aqueous phase were approximately constant and the exit rate coefficient decreased with monomer feed rate. Homogeneous nucleation is the dominant mechanism of production of particles, micellar nucleation occurs at the slowest feeding rate examined.
Enhanced chemical weathering as a geoengineering strategy to reduce atmospheric carbon dioxide, supply nutrients, and mitigate ocean acidification
Authors: Hartmann Jens , West A. Joshua , Renforth Phil , Köhler Peter , De La Rocha Christina L. , Wolf‐Gladrow Dieter A. , Dürr Hans H. , Scheffran Jürgen
Published: June 2013

Chemical weathering is an integral part of both the rock and carbon cycles and is being affected by changes in land use, particularly as a result of agricultural practices such as tilling, mineral fertilization, or liming to adjust soil pH. These human activities have already altered the terrestrial chemical cycles and land‐ocean flux of major elements, although the extent remains difficult to quantify. When deployed on a grand scale, Enhanced Weathering (a form of mineral fertilization), the application of finely ground minerals over the land surface, could be used to remove CO2 from the atmosphere. The release of cations during the dissolution of such silicate minerals would convert dissolved CO2 to bicarbonate, increasing the alkalinity and pH of natural waters. Some products of mineral dissolution would precipitate in soils or be taken up by ecosystems, but a significant portion would be transported to the coastal zone and the open ocean, where the increase in alkalinity would partially counteract “ocean acidification” associated with the current marked increase in atmospheric CO2. Other elements released during this mineral dissolution, like Si, P, or K, could stimulate biological productivity, further helping to remove CO2 from the atmosphere. On land, the terrestrial carbon pool would likely increase in response to Enhanced Weathering in areas where ecosystem growth rates are currently limited by one of the nutrients that would be released during mineral dissolution. In the ocean, the biological carbon pumps (which export organic matter and CaCO3 to the deep ocean) may be altered by the resulting influx of nutrients and alkalinity to the ocean. This review merges current interdisciplinary knowledge about Enhanced Weathering, the processes involved, and the applicability as well as some of the consequences and risks of applying the method.
Global atmospheric downward longwave radiation at the surface from ground‐based observations, satellite retrievals, and reanalyses
Authors: Wang Kaicun , Dickinson Robert E.
Published: June 2013

Atmospheric downward longwave radiation at the surface (Ld) varies with increasing CO2and other greenhouse gases. This study quantifies the uncertainties of current estimates of globalLdat monthly to decadal timescales and its global climatology and trends during the past decades by a synthesis of the existing observations, reanalyses, and satellite products. We find that currentLdobservations have a standard deviation error of ~3.5 W m−2on a monthly scale. Observations ofLdby different pyrgeometers may differ substantially for lack of a standard reference. The calibration of a pyrgeometer significantly affects its quantification of annual variability. Compared with observations collected at 169 global land sites from 1992 to 2010, theLdderived from state‐of‐the‐art satellite cloud observations and reanalysis temperature and humidity profiles at a grid scale of ~1° has a bias of ±9 W m−2and a standard deviation of 7 W m−2, with a nearly zero overall bias. The standard deviations are reduced to 4 W m−2over tropical oceans when compared toLdobservations collected by 24 buoy sites from 2002 to 2011. The −4 W m−2bias of satelliteLdretrievals over tropical oceans is likely because of the overestimation ofLdobservations resulting from solar heating of the pyrgeometer. Our best estimate of global meansLdfrom 2003 to 2010 are 342 ± 3 W m−2(global), 307 ± 3 W m−2(land), and 356 ± 3 W m−2(ocean). Estimates ofLdtrends are seriously compromised by the changes in satellite sensors giving changes of water vapor profiles.
Application of bayesian statistics to decision making during a clinical trial
Authors: Freedman Laurence S. , Spiegelhalter David J.
Published: June 2013

We describe the application of Bayesian methods to the monitoring and analysis of a trial of treatment for patients with advanced colorectal carcinoma. We discuss the choice of prior distribution and justify the use of a truncated normal distribution with a probability mass at zero difference. The stopping rule, based on the trials of the posterior distribution and a chosen range of equivalence, yields an upper boundary very close to the Pocock group sequential boundary. The Bayes stopping rule is quite sensitive to the amount of probability mass at zero in the prior distribution.
Incorporating probabilistic seasonal climate forecasts into river management using a risk‐based framework
Authors: Towler Erin , Roberts Mike , Rajagopalan Balaji , Sojda Richard S.
Published: June 2013

Despite the influence of hydroclimate on river ecosystems, most efforts to date have focused on using climate information to predict streamflow for water supply. However, as water demands intensify and river systems are increasingly stressed, research is needed to explicitly integrate climate into streamflow forecasts that are relevant to river ecosystem management. To this end, we present a five step risk‐based framework: (1) define risk tolerance, (2) develop a streamflow forecast model, (3) generate climate forecast ensembles, (4) estimate streamflow ensembles and associated risk, and (5) manage for climate risk. The framework is successfully demonstrated for an unregulated watershed in southwest Montana, where the combination of recent drought and water withdrawals has made it challenging to maintain flows needed for healthy fisheries. We put forth a generalized linear modeling (GLM) approach to develop a suite of tools that skillfully model decision‐relevant low flow characteristics in terms of climate predictors. Probabilistic precipitation forecasts are used in conjunction with the GLMs, resulting in season‐ahead prediction ensembles that provide the full risk profile. These tools are embedded in an end‐to‐end risk management framework that directly supports proactive fish conservation efforts. Results show that the use of forecasts can be beneficial to planning, especially in wet years, but historical precipitation forecasts are quite conservative (i.e., not very “sharp”). Synthetic forecasts show that a modest “sharpening” can strongly impact risk and improve skill. We emphasize that use in management depends on defining relevant environmental flows and risk tolerance, requiring local stakeholder involvement.
Désobéissance civile et libéralisme
Authors: Cervera-Marzal Manuel
Published: June 2013

Résumé.Des citoyens peuvent-ils désobéir à la loi, pourtant issue de la volonté majoritaire et de la décision du Parlement légitimement élu, au seul motif qu'elle leur semble injuste ? Face à la pensée conservatrice, tenante de l'ordre établi et réfractaire à la moindre transgression (« mieux vaut une injustice qu'un désordre »), la philosophie libérale contemporaine a fourni une défense de la légitimité démocratique de la désobéissance civile. Cependant, les justifications rawlsienne et habermassienne de la désobéissance civile semblent bien timorées dès qu'on accepte de les comparer à la pensée politique des activistes désobéissants eux-mêmes, à savoir Gandhi, Martin Luther King et Howard Zinn. Cette « pensée désobéissante » méconnue, voire occultée, vient révéler les insuffisances et les présupposés de la conception libérale de la désobéissance civile.

Abstract.Can citizens disobey the law, which comes from the will of the majority and the decision of the legitimately elected Parliament, merely because it seems to them unjust? Opposing conservative thought, which defends the established order and condemns any transgression, contemporary liberal thought has provided a defense of the democratic legitimacy of civil disobedience. However, the Rawlsian and Habermasian justifications of civil disobedience seem rather weak when compared to the political thought of disobedient activists themselves, namely Gandhi, Martin Luther King Jr. and Howard Zinn. This overlooked “disobedient thought” reveals the shortcomings and assumptions of the liberal concept of civil disobedience.
The genus Dirina (Roccellaceae, Arthoniales) revisited
Authors: TEHLER Anders , ERTZ Damien , IRESTEDT Martin
Published: June 2013

Dirina (Roccellaceae, Arthoniales) is a monophyletic genus of crustose, saxicolous or corticolous lichenized fungi. Twenty-four species are accepted in the genus, including nine new species: Dirina angolana, D. arabica, D. astridae, D. canariensis, D. indica, D. madagascariensis, D. pacifica, D. pallescens and D. sorocarpa. A phylogenetic hypothesis is presented based on data from four molecular markers, β-tubulin, ITS 1 and 2, nuLSU and RPB2, including all recognized Dirina species worldwide. New combinations proposed include Dirina badia for Roccellina badia, Dirina jamesii for Roccellina jamesii, Dirina candida for Chiodecton candidum and Dirina teichiodes for Lecidea teichiodes. Two species are reinstated: Dirina approximata and D. monothalamia (as a new name of Chiodecton africanum). Asexual morphs described earlier at the rank forma are no longer recognized as taxonomic units viz., Dirina catalinariae f. sorediata, D. insulana f. sorediata, D. massiliensis f. sorediata, D. paradoxa ssp. paradoxa f. sorediata and D. massiliensis f. aponina. One species, Dirina calcicola, is transferred to Fulvophyton and two other species, Dirina insulae-howensis and Dirina neozelandica, are transferred to Schismatomma. Dirina follmannii is not accepted in Dirina and placed as incertae sedis. A key to the species of Dirina is provided. Vicariance through plate tectonics and continental drift versus long distance dispersal to explain biogeographical patterns is discussed.
Lichen biogeography at the largest scales
Authors: ARCADIA Linda in
Published: June 2013

A quantitative cluster analysis of lichen distribution data demonstrates that the main biogeographical subdivision in the world's lichen biota is into a Gondwanan and a Laurasian element. Patterns at smaller scales mainly reflect local climate. Wallace's line is not a significant boundary for lichens. The Gondwana / Laurasia split also applies to lichenicolous fungi. To a considerable extent, it applies to many of the larger families and orders of lichens too, though at these ranks the affinities of the lichen biota of eastern Asia and temperate North America are sometimes ambiguous.
DSM-IV defined conduct disorder and oppositional defiant disorder: an investigation of shared liability in female twins
Authors: Knopik V. S. , Bidwell L. C. , Flessner C. , Nugent N. , Swenson L. , Bucholz K. K. , Madden P. A. F. , Heath A. C.
Published: June 2013

Background

DSM-IV specifies a hierarchal diagnostic structure such that an oppositional defiant disorder (ODD) diagnosis is applied only if criteria arenotmet for conduct disorder (CD). Genetic studies of ODD and CD support a combination of shared genetic and environmental influences but largely ignore the imposed diagnostic structure.

Method

We examined whether ODD and CD share an underlying etiology while accounting for DSM-IV diagnostic specifications. Data from 1446 female twin pairs, aged 11–19 years, were fitted to two-stage models adhering to the DSM-IV diagnostic hierarchy.

Results

The models suggested that DSM-IV ODD–CD covariation is attributed largely to shared genetic influences.

Conclusions

This is the first study, to our knowledge, to examine genetic and environmental overlap among these disorders while maintaining a DSM-IV hierarchical structure. The findings reflect primarily shared genetic influences and specific (i.e. uncorrelated) shared/familial environmental effects on these DSM-IV-defined behaviors. These results have implications for how best to define CD and ODD for future genetically informed analyses.
Intermediate representations exclude embodiment
Authors: Dove Guy
Published: June 2013

Given that Pickering & Garrod's (P&G's) account integrates language production and comprehension, it is reasonable to ask whether it is compatible with embodied cognition. I argue that its dependence on rich intermediate representations of linguistic structure excludes embodiment. Two options are available to supporters of embodied cognition: They can adopt a more liberal notion of embodiment or they can attempt to replace these intermediate representations with robustly embodied ones. Both of these options face challenges.
The role of action in verbal communication and shared reality
Authors: Echterhoff Gerald
Published: June 2013

In examining the utility of the action view advanced in the Pickering & Garrod (P&G) target article, I first consider its contribution to the analysis of language vis-à-vis earlier language-as-action approaches. Second, I assess the relation between coordinated joint action, which serves as a blueprint for dialogue coordination, and the experience of shared reality, a key concomitant and product of interpersonal communication.
Is there any evidence for forward modeling in language production?
Authors: Mylopoulos Myrto I. , Pereplyotchik David
Published: June 2013

The neurocognitive evidence that Pickering & Garrod (P&G) cite in favor of positing forward models in speech production is not compelling. The data to which they appeal either cannot be explained by forward models, or can be explained by a more parsimonious model.
Prediction is no panacea: The key to language is in the unexpected
Authors: Rabagliati Hugh , Bemis Douglas K.
Published: June 2013

For action systems, the critical task is to predict what will happen next. In language, however, the critical task is not to predict the next auditory event but to extract meaning. Reducing language to an action system, and putting prediction at center, mistakenly marginalizes our core capacity to communicate the novel and unpredictable.
When to simulate and when to associate? Accounting for inter-talker variability in the speech signal
Authors: Trude Alison M.
Published: June 2013

Pickering & Garrod's (P&G's) theory could be modified to describe how listeners rapidly incorporate context to generate predictions about speech despite inter-talker variability. However, in order to do so, the content of “impoverished” predicted percepts must be expanded to include phonetic information. Further, the way listeners identify and represent inter-talker differences and subsequently determine which prediction method to use would require further specification.
Seeking predictions from a predictive framework
Authors: Jaeger T. Florian , Ferreira Victor
Published: June 2013

We welcome the proposal to use forward models to understand predictive processes in language processing. However, Pickering & Garrod (P&G) miss the opportunity to provide a strong framework for future work. Forward models need to be pursued in the context of learning. This naturally leads to questions about what prediction error these models aim to minimize.
Forward models and their implications for production, comprehension, and dialogue
Authors: Pickering Martin J. , Garrod Simon
Published: June 2013

Our target article proposed that language production and comprehension are interwoven, with speakers making predictions of their own utterances and comprehenders making predictions of other people's utterances at different linguistic levels. Here, we respond to comments about such issues as cognitive architecture and its neural basis, learning and development, monitoring, the nature of forward models, communicative intentions, and dialogue.
Savings bank depositors in a crisis: Glasgow 1847 and 1857
Authors: Ross Duncan
Published: June 2013

Savings banks were created as a means to encourage the newly created working class to save for the uncertainties of urban industrial life. This article explores the success of the Savings Bank of Glasgow, and pays particular attention to the response of savers to the financial and commercial crises of 1847 and 1857. The crisis of 1847 was shallower but longer lasting in Glasgow, while that of 1857 was greatly exacerbated by local conditions in the short term, but of little long-term importance to savers. It suggests that, in both crises, some elements of contagion may have been present but that those who panicked in 1857 were systematically different from those who did not.
Theoretical assessment of graphene-metal contacts
Authors: Janthon Patanachai , Viñes Francesc , Kozlov Sergey M. , Limtrakul Jumras , Illas Francesc
Published: June 2013

Graphene-metal contacts have emerged as systems of paramount importance in the synthesis of high-quality and large-size patches of graphene and as vital components of nanotechnological devices. Herein, we study the accuracy of several density functional theory methods using van der Waals functionals or dispersive forces corrections when describing the attachment of graphene on Ni(111). Two different experimentally observed chemisorption states, top-fcc and bridge-top, were put under examination, together with the hcp-fcc physisorption state. Calculated geometric, energetic, and electronic properties were compared to experimental data. From the calculations, one finds that (i) predictions made by different methodologies differ significantly and (ii) optB86b-vdW functional and Grimme dispersion correction seem to provide the best balanced description of stability of physisorption and chemisorption states, the attachment strength of the latter on Ni(111) surface, the graphene-Ni(111) separation, and the bandstructure of chemisorbed graphene. The collation suggests that accurate and affordable theoretical studies on technologies based on graphene-metal contacts are already at hand.
TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: Phase diagrams and molecular dynamic simulations
Authors: Taha Mohamed , Lee Ming-Jer
Published: June 2013

Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol/acetonitrile/acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.
Strain-induced optical absorption properties of semiconductor nanocrystals
Authors: Zhang Ai , Luo Sheng , Ouyang Gang , Yang Guowei
Published: June 2013

As comparable to the spherical nanocrystals, the nanocrystals with non-spherical shape have fascinating properties induced by a large fraction of under-coordinated atoms located at end parts, including edges, vertexes, and side facets. Herein, taking into account the shell-core configuration of semiconductor nanospheres, nanocubes, and nanorods, we investigate the self-equilibrium strain on optical absorption properties from the perspective of atomistic origin. It has been found that the band gap of nanocrystals exhibits a pronounced blueshift compared with that of the bulk counterpart, and further shown that the band gap of nanospheres is different from that of naoncubes and nanorods. Moreover, we demonstrate that the shape effects have weak influences on the absorption coefficient when the crystal size approaches to a threshold value that is much smaller than the exciton Bohr radius at short wavelengths. Remarkably, the nanocubes have the largest deformation potential compared to the nanorods and nanospheres at fixed strain. The physical origin can be ascribed to the self-equilibrium strain induced by end effects that changes the bonding identifies, which leads to the variations of cohesive energy and entire Hamiltonian of nanocrystals. Our theoretical predictions not only are consistent with the experimental measurements and simulations, but also indicate the possible method on tunable optical properties of semiconductor nanocrystals.
Homogeneous connectivity of potential energy network in a solidlike state of water cluster
Authors: Akimoto Takuma , Kaneko Toshihiro , Yasuoka Kenji , Zeng Xiao Cheng
Published: June 2013

A novel route to the exponential trapping-time distribution within a solidlike state in water clusters is described. We propose a simple homogeneous network (SHN) model to investigate dynamics on the potential energy networks of water clusters. In this model, it is shown that the trapping-time distribution in a solidlike state follows the exponential distribution, whereas the trapping-time distribution in local potential minima within the solidlike state is not exponential. To confirm the exponential trapping-time distribution in a solidlike state, we investigate water clusters, (H2O)6 and (H2O)12, by molecular dynamics simulations. These clusters change dynamically from solidlike to liquidlike state and vice versa. We find that the probability density functions of trapping times in a solidlike state are described by the exponential distribution whereas those of interevent times of large fluctuations in potential energy within the solidlike state follow the Weibull distributions. The results provide a clear evidence that transition dynamics between solidlike and liquidlike states in water clusters are well described by the SHN model, suggesting that the exponential trapping-time distribution within a solidlike state originates from the homogeneous connectivity in the potential energy network.
Function space requirements for the single-electron functions within the multiparticle Schrödinger equation
Authors: Mohlenkamp Martin J.
Published: June 2013

Our previously described method to approximate the many-electron wavefunction in the multiparticle Schrödinger equation reduces this problem to operations on many single-electron functions. In this work, we analyze these operations to determine which function spaces are appropriate for various intermediate functions in order to bound the output. This knowledge then allows us to choose the function spaces in which to control the error of a numerical method for single-electron functions. We find that an efficient choice is to maintain the single-electron functions in L2 ∩ L4, the product of these functions in L1 ∩ L2, the Poisson kernel applied to the product in L4, a function times the Poisson kernel applied to the product in L2, and the nuclear potential times a function in L4/3. Due to the integral operator formulation, we do not require differentiability.
Trapped internal waves over topography: Non-Boussinesq effects, symmetry breaking and downstream recovery jumps
Authors: Soontiens Nancy , Stastna Marek , Waite Michael L.
Published: June 2013

It is well-known that in certain parameter regimes, the steady flow of a density stratified fluid over topography can yield large amplitude internal waves. We discuss an embedded boundary method to solve the Dubreil-Jacotin-Long (DJL) equation for steady-state, supercritical flows over topography in an inviscid, stratified fluid. The DJL equation is equivalent to the full set of stratified steady Euler equations and thus the waves we compute are exact nonlinear solutions. The numerical method presented yields far better scaling with increase in grid size than other iterative methods that have been used to solve this equation, and this in turn allows for a more thorough exploration of parameter space. For waves under the Boussinesq approximation, we contrast the properties of trapped waves over hill-like and valley-like topography, finding that the symmetry of freely propagating solitary waves when the stratification is reflected across the middepth is not present for trapped waves. We extend the derivation of the DJL equation to the non-Boussinesq case and discuss the effect of the new, non-Boussinesq terms on the structure of the trapped waves, finding that the sharp transition between large and small amplitude waves observed under the Boussinesq approximation is much more gradual when the Boussinesq approximation is relaxed. Finally, we demonstrate the existence of asymmetric steady states over hill-like topography where the flow is subcritical upstream of the topography but transitions to supercritical somewhere over the hill. Waves in this new class of exact solutions are related to so-called downstream recovery jumps predicted on the basis of hydrostatic (shallow water) theories, but when breaking does not occur the recovery jump does not stop propagating downstream and an asymmetric state across the topography maximum is reached for long times.
Motion of a bubble ring in a viscous fluid
Authors: Cheng M. , Lou J. , Lim T. T.
Published: June 2013

In this paper, lattice Boltzmann method was undertaken to study the dynamics of a vortex ring bubble (or bubble ring) in a viscous incompressible fluid. The study is motivated partly by our desire to assess whether a bubble ring keeps increasing its radius and decreasing its rise velocity as it rises through fluid as was predicted by Turner [“Buoyant vortex rings,” Proc. R. Soc. London, Ser. A 239, 61 (1957)]10.1098/rspa.1957.0022 and Pedley [“The toroidal bubble,” J. Fluid Mech. 32, 97 (1968)]10.1017/S0022112068000601, or does the ring like a rising bubble, eventually reaches a steady state where its radius and velocity remain constant as was predicted by Joseph et al. [Potential Flows of Viscous and Viscoelastic Fluids (Cambridge University Press, 2008)]. The parameters investigated included ring circulation, Reynolds number, density ratio and Bond number. Our numerical results show that a rising bubble ring increases its radius and decreases its velocity, but the process is interrupted by ring instability that eventually causes it to break up into smaller bubbles. This finding is consistent with the stability analysis by Pedley, who predicted that a bubble ring has a finite lifespan and is ultimately destroyed by surface tension instability. Furthermore, it is found that increasing initial circulation has a stabilizing effect on a bubble ring while increasing Reynolds number or Bond number hastens ring instability, resulting in an earlier break up into smaller bubbles; the number of bubbles depends on the wavenumber of the perturbation.
Two opposite hysteresis curves in semiconductors with mobile dopants
Authors: Sung Lee Jae , Buhm Lee Shin , Kahng Byungnam , Won Noh Tae
Published: June 2013

Semiconductors with mobile dopants (SMDs), which are distinct from conventional semiconductors, exhibit hysteretic current-voltage curves. The fundamental feature of this hysteresis curve is that it exhibits two oppositely rotating directions, whose origin is not clarified yet. Here, we investigate microscopic origin of the two types of curves and show that they result from the spatial inhomogeneity of the mobile dopant distribution in the SMD. In particular, we observed an abnormal modulation of the electronic energy band due to mobile dopants; lower (higher) density of dopants near a metal-semiconductor interface lead to higher (lower) conductance, whereas the conventional ionic models predict the reverse behaviors.
Ideal magnetohydrodynamic stability of configurations without nested flux surfaces
Authors: Helander P. , Newton S. L.
Published: June 2013

Existing numerical tools for calculating the MHD stability of magnetically confined plasmas generally assume the existence of nested flux surfaces. These tools are therefore not immediately applicable to configurations with magnetic islands or regions with an ergodic magnetic field. However, in practice, these islands or ergodic regions are often small, and their effect on MHD stability can then be evaluated using a perturbation theory developed in the present paper. This procedure allows the effect of the broken magnetic topology on the stability of each eigenmode to be calculated without requiring any knowledge about the perturbed eigenfunctions.
Insertion of a Si layer to reduce operation current for resistive random access memory applications
Authors: Chen Yu-Ting , Chang Ting-Chang , Peng Han-Kuang , Tseng Hsueh-Chih , Huang Jheng-Jie , Yang Jyun-Bao , Chu Ann-Kuo , Young Tai-Fa , Sze Simon M.
Published: June 2013

In this study, a reduction of low resistive state (LRS) current is discovered in a V:SiO2/Si bi-layer structure with the addition of a Si layer. A Pt/V:SiO2/TiN structure is fabricated as the standard sample. The results of conduction mechanism analyses for LRS indicate that a SiO2 interfacial layer forms through oxidation of the inserted Si layer after the set process. The LRS current reduction can be attributed to the formation of this SiO2 layer. In addition, self-compliance behavior for the bi-layer structure during the set process further proves the existence of this SiO2 buffer layer in LRS.
Transparent and flexible multi-layer films with graphene recording layers for optical data storage
Authors: Xing Fei , Chen Xu-Dong , Liu Zhi-Bo , Zhang Qian , Yan Xiao-Qing , Chen Yongsheng , Tian Jian-Guo
Published: June 2013

Based on the polarization-sensitive absorption of graphene under conditions of total internal reflection, we demonstrate the fabrication and reading of transparent and flexible multi-layer-film optical data storage media based on graphene recording layers. We report a realization of the process of data writing-transferring-reading by repeatedly transferring recorded graphene and its strong polarization effect. The reading results show a high signal-to-noise ratio and stability and low crosstalk interference between the layers. In addition, the graphene-based multi-layer-film optical data storage medium has a high transparency and flexibility. The high signal-to-noise ratio remains stable after the structure is bent 1000 times.
Social welfare through guaranteed wage employment: experience of National Rural Employment Guarantee Scheme in an Indian state
Authors: Swain Pranaya Kumar , Ray Sthitapragyan
Published: June 2013

Recognition of the significance of public wage employment programmes in tackling unpredictable community “covariate” shocks and ensuring livelihood security of the rural poor has led to the enactment of the Mahatma Gandhi National Rural Employment Guarantee Act, with state guarantee of work. Implementation of the Act, our empirical findings tell us, has become the site of tangible exchanges between state and society, with factors such as the level of material support for it, the balance of power between the local state and the poor on the ground, and the larger socio-economic structure determining programme outcomes.
The post-crisis European social model: developing or dismantling social investments?
Authors: Kvist Jon
Published: June 2013

This paper offers a theoretical and empirical contribution to our understanding of the changing European social models in wake of the economic crisis and the promotion of social investments by the European Commission. Theoretically, the article provides a conceptual framework for comparative macro-analysis of social investments that takes into account how social investment policies and returns vary over the life-course and are interdependent. Empirically, the article uses this conceptual framework to examine whether EU policy strategies and national welfare reforms follow a social investment approach. Analysing developments of social investment strategies and policies in three life-stages, the article finds that many EU strategies embody elements of a social investment strategy whereas the impact of the crisis on the national level differs across countries, life-stages, and policies. In most countries, the overall policy impact of the crisis seems to be small on childcare coverage, large on youth polarization, and to increase retirement ages. The crisis will be felt in years to come with reduced life-income for younger cohorts, lower fertility laying the ground for intergenerational conflicts, and migration of skilled youth implying returns of social investments made in southern parts of Europe benefitting northern parts. That said, the overall evidence points towards social investments taking a larger role in Europe after the crisis. However, the result is unlikely to become a uniform European social investment model as the countries most in need of social investments are also the countries least likely to develop high-quality social investments.
Can restoration of afforested peatland regulate pests and disease?
Authors: Gilbert Lucy
Published: June 2013

Government policies are driving landscape‐scale changes in land use to provide ecosystem services; but there may be unconsidered cascading effects. A major land use change targeted for regulating climate and biodiversity is peatland restoration. This will cause changes in vegetation and, potentially, keystone species such as large herbivores, which are the main hosts to Ixodes ricinus (L.) ticks, the most important vector of disease‐causing pathogens in Europe.

This study tested the impact of restoring peatlands from conifer forestry on Ixodes ricinus abundance and explored the likely mechanisms. Large‐scale surveys of Ixodes ricinus, vertebrate herbivores and vegetation were conducted in adjacent areas of forest, bog and areas felled 5–13 years previously.

Questing tick abundance was greatest in forest and almost absent from blanket bog, with intermediate numbers in felled areas, where ticks were more abundant in young than in old felled areas.

The likely mechanisms for these variations in tick abundance were deer habitat preferences (bog was the least preferred habitat) and ground vegetation height or canopy cover, which are generally associated with alternative tick hosts and micro‐climates that aid tick questing and survival.

Synthesis and applications. Felling conifer forest to restore peatlands could produce a dramatic decline in tick abundance throughout the restoration process, with implications for disease risk. Therefore, a further ecosystem service of peatlands in addition to climate, biodiversity and water regulation is regulating pests and disease. Deer management and procedures that speed up the restoration process are likely to enhance the effect during the intermediate stages.
18FDG PET and PET‐CT for the detection of bone metastases in patients with head and neck cancer. A meta‐analysis
Authors: Yi Xuelian , Fan Min , Liu Yilin , Zhang Hongting , Liu Shixi
Published: June 2013

Introduction

We performed a meta‐analysis to evaluate 18FDG PET/PET‐CT for the detection of bone metastases in patients with head and neck cancer.

Methods

We calculated sensitivities, specificities, likelihood ratios, and constructed summary receiver operating characteristic curves for PET and PET‐CT, respectively. We also compared the performance of PET/PET‐CT with that of bone scintigraphy by analysing studies that had also used bone scintigraphy on the same patients.

Results

Across 9 PET studies (1621 patients) and 10 PET‐CT studies (1291 patients), sensitivity and specificity of PET were 0.81 and 0.99, and of PET‐CT were 0.89 and 0.99, respectively. In 5 comparative studies (1184 patients), sensitivity and specificity of PET/PET‐CT were 0.85 and 0.98, and of bone scintigraphy were 0.55 and 0.98, respectively.

Conclusions

18FDG PET and PET‐CT have high sensitivity and accuracy for the detection of bone metastasis in patients with head and neck cancer.
Improving reading comprehension in reading and listening settings: The effect of two training programmes focusing on metacognition and working memory
Authors: Carretti Barbara , Caldarola Nadia , Tencati Chiara , Cornoldi Cesare
Published: June 2013

Background

Metacognition and working memory (WM) have been found associated with success in reading comprehension, but no studies have examined their combined effect on the training of reading comprehension. Another open question concerns the role of listening comprehension: In particular, it is not clear whether training to improve reading comprehension must necessarily be based on processing written material or whether, as suggested in a recent study by Clarke et al. (2010, Psychol. Sci., 21, 1106), a programme based on verbal language could also be effective.

Aims

The study examined the feasibility of improving text comprehension in school children by comparing the efficacy of two training programmes, both involving metacognition and WM, but one based on listening comprehension, the other on reading comprehension.

Participants

The study involved a sample of 159 pupils attending eight classes in the fourth and fifth grades (age range 9–11 years).

Method

The listening and reading programmes focused on the same abilities/processes strictly related to text comprehension, and particularly metacognitive knowledge and control, WM (per se and in terms of integrating information in a text). The training programmes were implemented by school teachers as part of the class's normal school activities, under the supervision of experts. Their efficacy was compared with the results obtained in an active control group that completed standard text comprehension activities.

Results

Our results showed that both the training programmes focusing on specific text comprehension skills were effective in improving the children's achievement, but training in reading comprehension generated greater gains than the listening comprehension programme.

Conclusions

Our study suggests that activities focusing specifically on metacognition and WM could foster text comprehension, but the potential benefit is influenced by the training modality, that is, the Reading group obtained greater and longer‐lasting improvements than the Active control or Listening groups.
Urban Land Restitution and the Struggle for Social Citizenship in South Africa
Authors: Beyers Christiaan
Published: June 2013

Reintegrating the city is a priority of social justice and development in many urban centres of the ‘South’ that bear the legacy of forced displacement. In South Africa, much of the land restitution programme has thus far focused on urban areas. In certain large cluster claims involving the transfer and development of significant tracts of well‐placed land, restitution has presented the prospect of altering landed property regimes in the heart of the city. The predominantly rural and economic emphasis in scholarship and policy debate on land reform in South Africa — which reflects historical trends in development studies — has led to a narrowed vision of what is at stake in urban land restitution. Complex interventions aimed at redressing urban spatial segregation can potentially alter the relationship between citizens, institutions and urban space in ways that expand the possibilities for social and political agency in sites that are strategically important for influencing the direction of change more broadly. A key, as yet unrealized, challenge is how to articulate such struggles for a ‘right to the city’ with efforts at redressing the spatialization of poverty on the urban periphery.