bluuebunny/crossref_metadata_2025 huggingface dataset:
Confessions of a Sceptical Francophile
Authors: Scruton Roger
Published: October 2012

In post-war France we have witnessed an upsurge in philosophical and quasi-philosophical literature, much of it nonsense and all of it radically politicised. What is the explanation of this? I advance the thesis that the post-1968 literary scene expresses a bid for a new kind of social membership, and that it is the hunger for membership that explains not only the intellectual structure of this literature but also its world-wide influence. I also suggest that there survives in this literature both an intellectual agenda and a historical memory, in which the war-time experience of France is all-important. In the course of my argument I try to explain the radical difference between analytical philosophy, which permits its practitioners to have unorthodox (i.e. non-left-wing) political views, and a particular post-war French intellectual tradition, which has until recently allowed no such deviation from its tacit norms.
Russell on Knowledge of Universals by Acquaintance
Authors: Giaquinto M.
Published: October 2012

Russell's book The Problems of Philosophy was first published a hundred years ago.1 A remarkable feature of this enduring text is the glint of Platonism it presents on a dark empiricist sea: while our knowledge of physical objects is entirely mediated by direct awareness of sense data, we can also have direct awareness of certain universals, Russell claims.2 This is questionable, even if one has no empiricist inclination. Universals are abstract, hence causally inert. How, then, can we have any knowledge of them, direct or indirect? This paper is about Russell's answer to that question. I will argue that given some modification and elaboration of Russell's views, his claim that some universals are knowable by acquaintance is plausible.
Tabula Rasaand Human Nature
Authors: Duschinsky Robert
Published: October 2012

It is widely believed that the philosophical concept of ‘tabula rasa’ originates with Locke'sEssay Concerning Human Understandingand refers to a state in which a child is as formless as a blank slate. Given that both these beliefs are entirely false, this article will examine why they have endured from the eighteenth century to the present. Attending to the history of philosophy, psychology, psychiatry and feminist scholarship it will be shown how the image of thetabula rasahas been used to signify an originary state of formlessness, against which discourses on the true nature of the human being can differentiate their position. Thetabula rasahas operated less as a substantive position than as a whipping post. However, it will be noted that innovations in psychological theory over the past decade have begun to undermine such narratives by rendering unintelligible the idea of an ‘originary’ state of human nature.
Between Autonomy and State Regulation: J.S. Mill's Elastic Paternalism
Authors: Cohen-Almagor Raphael
Published: October 2012

This paper analyses J.S. Mill's theory on the relationships between individual autonomy and State powers. It will be argued that there is a significant discrepancy between Mill's general liberal statements aimed to secure individual largest possible autonomy and the specific examples which provide the government with quite wide latitude for interference in the public and private spheres. The paper outlines the boundaries of government interference in the Millian theory. Subsequently it describes Mill's elastic paternalism designed to prevent people from inflicting harm upon others as well as upon themselves, from soft paternalism on issues like compulsory education to hard paternalism on very private matters such as marriage, having children, and divorce by consent.
A 20-year multi-follow-up of hallucinations in schizophrenia, other psychotic, and mood disorders
Authors: Goghari V. M. , Harrow M. , Grossman L. S. , Rosen C.
Published: October 2012

Background

Hallucinations are a major aspect of psychosis and a diagnostic feature of both psychotic and mood disorders. However, the field lacks information regarding the long-term course of hallucinations in these disorders. Our goals were to determine the percentage of patients with hallucinations and the relationship between hallucinations and recovery, and work attainment.

Method

The present study was a prospective evaluation of the 20-year trajectory of hallucinations in 150 young patients: 51 schizophrenia, 25 schizoaffective, 25 bipolar with psychosis, and 49 unipolar depression. The patients were studied at an index phase of hospitalization for hallucinations, and then reassessed longitudinally at six subsequent follow-ups over 20 years.

Results

The longitudinal course of hallucinations clearly differentiated between schizophrenia and bipolar disorder with psychosis, and suggested some diagnostic similarities between schizophrenia and schizoaffective disorder, and between bipolar disorder and schizoaffective disorder and depression. Frequent or persistent hallucinatory activity over the 20-year period was a feature of 40–45% of schizophrenia patients. The early presence of hallucinations predicted the lack of future periods of recovery in all patients. Increased hallucinatory activity was associated with reduced work attainment in all patients.

Conclusions

This study provides data on the prospective longitudinal course of hallucinations, which were previously unavailable to the field, and are one of the key features of psychosis in major psychiatric disorders. This information on the clinical course of major psychiatric disorders can inform accurate classification and diagnosis.
Seed germination, hydrothermal time models and the effects of global warming on a threatened high Andean tree species
Authors: Gareca Edgar E. , Vandelook Filip , Fernández Milton , Hermy Martin , Honnay Olivier
Published: October 2012

Seed germination is a crucial event in a plant's life cycle. Because temperature and water availability are important regulators of seed germination, this process will likely be influenced by global warming. Insight into the germination process under global warming is thus crucial, and requires the study of a wide range of water availability and temperature conditions. As hydrothermal time (HTT) models evaluate seed germination for any combination of water potential and temperature, they can be suitable to predict global warming effects on seed germination. We studied the germination characteristics of the high Andean endemic tree speciesPolylepis besseri(Rosaceae), using HTT models. We were especially interested in the potential effects of global warming on seed germination. Assembly of HTT models forP. besseriwas fairly straightforward due to the lack of a seed dormancy mechanism. The models allowed prediction ofPolylepisgermination under constant and alternating temperatures. Initially, a global warming induced increase in the field minimum and mean temperature will increaseP. besserigermination, but as maximum temperatures rise above the optimum temperature for the species, seed germination will become jeopardized. Effects of global warming on seed germination are currently considerably underexplored. HTT models prove to be useful tools to study a plant species' general germination characteristics, and how they may become affected under global warming. For the endemic mountain tree speciesP. besseri, we predict an increase, followed by a decrease of seed germination under global warming.
Framework for Research on Children's Reactions to Disasters and Terrorist Events
Authors: Pfefferbaum Betty , Noffsinger Mary A. , Sherrieb Kathleen , Norris Fran H.
Published: October 2012

Clinical work and research relative to child mental health during and following disaster are especially challenging due to the complex child maturational processes and family and social contexts of children's lives. The effects of disasters and terrorist events on children and adolescents necessitate diligent and responsible preparation and implementation of research endeavors. Disasters present numerous practical and methodological barriers that may influence the selection of participants, timing of assessments, and constructs being investigated. This article describes an efficient approach to guide both novice and experienced researchers as they prepare to conduct disaster research involving children. The approach is based on five fundamental research questions: “Why?, Who?, When?, What?, andHow?” Addressing each of the “fourWs” will assist researchers in determining “How” to construct and implement a study from start to finish. A simple diagram of the five questions guides the reader through the components involved in studying children's reactions to disasters. The use of this approach is illustrated with examples from disaster mental health studies in children, thus simultaneously providing a review of the literature.

PfefferbaumB,NoffsingerMA,SherriebK,FranH.,NorrisFH..Framework for research on children's reactions to disasters and terrorist events.Prehosp Disaster Med.2012;27(6):1-10.
Temporal and crustal effects on differentiation of tholeiite to calcalkaline and ferro‐trachytic suites, High Lava Plains, Oregon, USA
Authors: Streck Martin J. , Grunder Anita L.
Published: October 2012

Strongly bimodal, basalt‐rhyolite volcanism of the High Lava Plains Province of Oregon followed the Middle Miocene flood basalts of the Pacific Northwest and extends to recent time. During the 8 m.y. of volcanism recorded in the central High Lava Plains, in western Harney Basin, three distinct mafic magmatic trends originate from primitive high‐alumina olivine tholeiites (HAOT); they are tholeiitic, calcalkaline and ferro‐trachytic. Tholeiitic basalts occur throughout the history and their compositions are derived by crystal fractionation while traversing the crust and mixing with evolved mafic magmas. Scavenging of apatite from crustal rocks and minor contamination with felsic melts accounts for P, incompatible element enrichments and increasing tilts of incompatible element patterns with differentiation. The calcalkaline mafic suite occurs in temporal association with abundant silicic volcanism and is the only suite with Fe decreasing with Mg. Calcalkaline compositions are derived from evolved tholeiitic basalt by crystal fractionation coupled with assimilation of felsic crust or crustal melts. The ferro‐trachytic suite occurs mainly late, is highly enriched in incompatible element with patterns parallel to tholeiites from which it is derived by protracted fractionation and recharge. The three suites primarily reflect changes in magma flux and crustal interactions in time. High magma flux promotes crustal melting and contamination of tholeiite to make the calcalkaline suite. On the other hand, ferrotrachytic magmas erupted mainly late in the sequence, during magmatic waning and after significant basaltification of the crust.
Sea level trends, interannual and decadal variability in the Pacific Ocean
Authors: Zhang Xuebin , Church John A.
Published: October 2012

Linear trend analysis is commonly applied to quantify sea level change, often over short periods because of limited data availability. However, the linear trend computed over short periods is complicated by large‐scale climate variability which can affect regional sea level on interannual to inter‐decadal time scales. As a result, the meaning of a local linear sea level trend over the short altimeter era (since 1993; less than 20 years) is unclear, and it is not straightforward to distinguish the regional sea level changes associated with climate change from those associated with natural climate variability. In this study, we use continuous near‐global altimeter measurements since 1993 to attempt to separate interannual and decadal sea level variability in the Pacific from the sea level trend. We conclude that the rapid rates of sea level rise in the western tropical Pacific found from a single variable linear regression analysis are partially due to basin‐scale decadal climate variability. The negligible sea level rise, or even falling sea level, in the eastern tropical Pacific and US west coast is a result of the combination of decreasing of sea level associated with decadal climate variability and a positive sea level trend. The single variable linear regression analysis only accounts for slightly more than 20% of the observed variance, whereas a multiple variable linear regression including filtered indices of the El Nino‐Southern Oscillation and the Pacific Decadal Oscillation accounts for almost 60% of the observed variance.
Enigmatic very low frequency tremors beneath the Shonai Plain in northeastern Japan
Authors: Nishida K. , Shiomi K.
Published: October 2012

Recently, dense and sensitive modern seismic networks have revealed tectonic and volcanic tremors. Although most studies of seismic tremors focused on these two types, other types of tremor activities also exist. To detect such tremor activities, we analyzed data from the Hi‐net high‐sensitivity accelerometers (tiltmeters) between June 2004 and June 2006. The results elucidate very low frequency (VLF) Love wave tremors with a typical frequency of 0.085 Hz beneath the Shonai Plain in northeastern Japan. The tremor activity lasted for several days and occurred several times per month in winter. The activity was triggered by secondary microseisms, which provide a proxy for local ocean swell activity. A possible source is a subhorizontal crack coupled with a fluid reservoir at the bottom of the sedimentary layer. All the observed features suggest that hydrologic phenomena are potential sources of VLF tremors. Because similar hydrologic phenomena can be expected even in tectonically and volcanically inactive regions, modern array observations by broadband seismometers may reveal similar hydrologic tremors in such regions.
Insights into the mechanisms and timescales of pluton assembly from deformation patterns of mafic enclaves
Authors: Caricchi Luca , Annen Catherine , Rust Alison , Blundy Jon
Published: October 2012

We propose a novel method to constrain both timescales and assembly styles of intrusive bodies using the strain recorded by mafic enclaves, a common component of granitic rocks. Petrology, thermal modeling, and magma rheology are combined to investigate the evolution of strain recorded by enclaves during the piecemeal assembly of a pluton growing at various rates of magma input. The different compositions (and hence phase relations) of host magma and enclaves limits homogeneous deformation of these two materials to restricted temperature ranges, which we term “windows of mutual deformability.” Outside these windows only the less viscous host granite records any appreciable deformation and enclaves are mainly transported as rigid objects. The temporal and spatial development of the windows of mutual deformability reflects the emplacement rate of magmas into the pluton. Consequently, the radial distribution of strain recorded by enclaves can provide a picture of the thermal and rheological evolution of a magmatic body during its construction. Our approach is applied to deformation patterns of mafic enclaves in the Lago della Vacca Complex (LVC) of the Adamello Massif (Italy), to estimate the timescales of pluton emplacement. Our calculations suggest total emplacement timescales of the order 50 to 150 ky, in excellent agreement with recent high precision radiometric dating of zircons from the LVC.
Ganga‐Brahmaputra river discharge from Jason‐2 radar altimetry: An update to the long‐term satellite‐derived estimates of continental freshwater forcing flux into the Bay of Bengal
Authors: Papa Fabrice , Bala Sujit K. , Pandey Rajesh K. , Durand Fabien , Gopalakrishna V. V. , Rahman Atiqur , Rossow William B.
Published: October 2012

This paper discusses the use of Jason‐2 radar altimeter measurements to estimate the Ganga‐Brahmaputra surface freshwater flux into the Bay of Bengal for the period mid‐2008 to December 2011. A previous estimate was generated for 1993–2008 using TOPEX‐Poseidon, ERS‐2 and ENVISAT, and is now extended using Jason‐2. To take full advantages of the new availability of in situ rating curves, the processing scheme is adapted and the adjustments of the methodology are discussed here. First, using a large sample of in situ river height measurements, we estimate the standard error of Jason‐2–derived water levels over the Ganga and the Brahmaputra to be respectively of 0.28 m and 0.19 m, or less than ∼4% of the annual peak‐to‐peak variations of these two rivers. Using the in situ rating curves between water levels and river discharges, we show that Jason‐2 accurately infers Ganga and Brahmaputra instantaneous discharges for 2008–2011 with mean errors ranging from ∼2180 m3/s (6.5%) over the Brahmaputra to ∼1458 m3/s (13%) over the Ganga. The combined Ganga‐Brahmaputra monthly discharges meet the requirements of acceptable accuracy (15–20%) with a mean error of ∼16% for 2009–2011 and ∼17% for 1993–2011. The Ganga‐Brahmaputra monthly discharge at the river mouths is then presented, showing a marked interannual variability with a standard deviation of ∼12500 m3/s, much larger than the data set uncertainty. Finally, using in situ sea surface salinity observations, we illustrate the possible impact of extreme continental freshwater discharge event on the northern Bay of Bengal as observed in 2008.
Estimation of clear‐sky land surface longwave radiation from MODIS data products by merging multiple models
Authors: Wu Haoran , Zhang Xiaotong , Liang Shunlin , Yang Hua , Zhou Gongqi
Published: October 2012

The surface longwave radiation budget plays an important role in the Earth's climate system. Remote sensing provides the most practical way to map surface longwave radiation on a large scale and at a high spatial resolution. In this paper, we evaluate both surface downward longwave radiation (DLR) and upwelling longwave radiation (ULR) models under clear‐sky conditions from MODIS data products. There are multiple DLR models available with variable uncertainties, and the Bayesian Model Averaging (BMA) method is incorporated in this study to combine the predictive distribution of these models for better accuracy. The integrated estimates for DLR based on the BMA method have lower root‐mean‐square errors (RMSEs) and higher coefficients of determination (R2) than the best individual model. The RMSEs decreased by approximately 10 W/m2 at two forest sites and by approximately 4 W/m2 at other sites. The R2value increased at each site by more than 0.05. Two models for calculating the surface upwelling longwave radiation (ULR) are also evaluated at 16 sites. The results show that both the land surface temperature (LST)–emissivity method and the direct method, the Wang‐U model underestimate the clear‐sky ULR. The validation results show that the surface net longwave radiation (NLR) estimated using DLR estimates based on the BMA method and ULR estimates based on the LST‐emissivity method is the most accurate.
An intense traveling airglow front in the upper mesosphere–lower thermosphere with characteristics of a bore observed over Alice Springs, Australia, during a strong 2 day wave episode
Authors: Walterscheid R. L. , Hecht J. H. , Gelinas L. J. , Hickey M. P. , Reid I. M.
Published: October 2012

The Aerospace Corporation's Nightglow Imager observed a large step function change in airglow in the form of a traveling front in the OH Meinel (OHM) and O2atmospheric (O2A) airglow emissions over Alice Springs, Australia, on 2 February 2003. The front exhibited nearly a factor of 2 stepwise increase in the OHM brightness and a stepwise decrease in the O2A brightness. There was significant (∼25 K) cooling behind the airglow fronts. The OHM airglow brightness behind the front was among the brightest for Alice Springs that we have measured in 7 years of observations. The event was associated with a strong phase‐locked 2 day wave (PL/TDW). We have analyzed the wave trapping conditions for the upper mesosphere and lower thermosphere using a combination of data and empirical models and found that the airglow layers were located in a region of ducting. The PL/TDW‐disturbed wind profile was effective in supporting a high degree of ducting, whereas without the PL/TDW the ducting was minimal or nonexistent. The change in brightness in each layer was associated with a strong leading disturbance followed by a train of weak barely visible waves. In OHM the leading disturbance was an isolated disturbance resembling a solitary wave. The characteristics of the wave train suggest an undular bore with some turbulent dissipation at the leading edge.
Ice flow sensitivity to geothermal heat flux of Pine Island Glacier, Antarctica
Authors: Larour E. , Morlighem M. , Seroussi H. , Schiermeier J. , Rignot E.
Published: October 2012

Model projections of ice flow in a changing climate are dependent on model inputs such as surface elevation, bedrock position or surface temperatures, among others. Of all these inputs, geothermal heat flux is the one for which uncertainty is greatest. In the area of Pine Island Glacier, Antarctica, available data sets differ by up to a factor of 2.5. Here, we evaluate the impact of such uncertainty on ice flow, using sampling analyses based on the Latin‐Hypercube method. First, we quantify the impact of geothermal heat flux errors on ice hardness, a thermal parameter that critically controls the magnitude of ice flow. Second, we quantify the impact of the same errors on mass balance, specifically on the mass flux advecting through thirteen fluxgates distributed across Pine Island Glacier. We contrast our results with similar uncertainties generated by errors in the specification of ice thickness. Model outputs indicate that geothermal heat flux errors yield uncertainties on ice hardness on the order of 5–7%, with maximum uncertainty reaching 15%. Resulting uncertainties in mass balance remain however below 1%. We discuss the uncertainty distribution and its relationship to the amount of heat available at the base of the ice sheet from friction, viscous and geothermal heating. We also show that comparatively, errors in ice thickness contribute more to model uncertainty than errors in geothermal heat flux, especially for fast‐flowing ice streams.
ImprimatinC1, a novel plant immune-priming compound, functions as a partial agonist of salicylic acid
Authors: Noutoshi Yoshiteru , Jikumaru Yusuke , Kamiya Yuji , Shirasu Ken
Published: October 2012

Plant activators are agrochemicals that protect crops from pathogens. They confer durable resistance to a broad range of diseases by activating intrinsic immune mechanisms in plants. To obtain leads regarding useful compounds, we have screened a chemical library using an established method that allows selective identification of immune-priming compounds. Here, we report the characterisation of one of the isolated chemicals, imprimatinC1 and its structural derivative imprimatinC2. ImprimatinC1 functions as a weak analogue of salicylic acid (SA) and activates the expression of defence-related genes. However, it lacks antagonistic activity toward jasmonic acid. Structure-activity relationship analysis suggests that imprimatinC1 and C2 can be metabolised to 4-chlorobenzoic acid and 3,4-chlorobenzoic acid, respectively, to function in Arabidopsis. We also found that imprimatinC1 and C2 and their potential functional metabolites acted as partial agonists of SA. Thus, imprimatinC compounds could be useful tools for dissecting SA-dependent signal transduction pathways.
Multi-temperature representation of electron velocity distribution functions. I. Fits to numerical results
Authors: Haji Abolhassani A. A. , Matte J.-P.
Published: October 2012

Electron energy distribution functions are expressed as a sum of 6–12 Maxwellians or a sum of 3, but each multiplied by a finite series of generalized Laguerre polynomials. We fitted several distribution functions obtained from the finite difference Fokker-Planck code “FPI” [Matte and Virmont, Phys. Rev. Lett. 49, 1936 (1982)] to these forms, by matching the moments, and showed that they can represent very well the coexistence of hot and cold populations, with a temperature ratio as high as 1000. This was performed for two types of problems: (1) the collisional relaxation of a minority hot component in a uniform plasma and (2) electron heat flow down steep temperature gradients, from a hot to a much colder plasma. We find that the multi-Maxwellian representation is particularly good if we accept complex temperatures and coefficients, and it is always better than the representation with generalized Laguerre polynomials for an equal number of moments. For the electron heat flow problem, the method was modified to also fit the first order anisotropy f1(x,v,t), again with excellent results. We conclude that this multi-Maxwellian representation can provide a viable alternative to the finite difference speed or energy grid in kinetic codes.
A molecular dynamics study of the thermal properties of thorium oxide
Authors: Martin Paul , Cooke David J. , Cywinski Robert
Published: October 2012

There is growing interest in the exploitation of the thorium nuclear fuel cycle as an alternative to that of uranium. As part of a wider study of the suitability of thorium dioxide (thoria) as a nuclear fuel, we have used molecular dynamics to investigate the thermal expansion, oxygen diffusion, and heat capacity of pure thoria and uranium doped (1-10%) thoria between 1500 K and 3600 K. Our results indicate that the thermal performance of the thoria matrix, even when doped with 10%U, is comparable to, and possibly better than, that of UO2.
Silicon nanoparticle-ZnS nanophosphors for ultraviolet-based white light emitting diode
Authors: Stupca Matthew , Nayfeh Osama M. , Hoang Tuan , Nayfeh Munir H. , Alhreish Bahjat , Boparai Jack , AlDwayyan Abdullah , AlSalhi Mohamad
Published: October 2012

Present red phosphor converters provide spectra dominated by sharp lines and suffer from availability and stability issues which are not ideal for color mixing in display or solid state lighting applications. We examine the use of mono dispersed 3 nm silicon nanoparticles, with inhomogeneously broadened red luminescence as an effective substitute for red phosphors. We tested a 3-phase hybrid nanophosphor consisting of ZnS:Ag, ZnS:Cu,Au,Al, and nanoparticles. Correlated color temperature is examined under UV and LED pumping in the range 254, 365–400 nm. The temperature is found reasonably flat for the longer wavelengths and drops for the shorter wavelengths while the color rendering index increases. The photo stability of the phosphors relative to the silicon nanoparticles is recorded. The variation in the temperature is analyzed in terms of the strength of inter-band–gap transition and continuum band to band transitions.
Low frequency electromagnetic oscillations in dense degenerate electron-positron pair plasma, with and without ions
Authors: Khan S. A. , Ayub M. K. , Ahmad Ali
Published: October 2012

Quantum plasma oscillations are studied in a strongly magnetized, ultra-dense plasma with degenerate electrons and positrons. The dispersive role of electron and positron quantum effects on low frequency (in comparison to electron cyclotron frequency) shear electromagnetic wave is investigated by employing hydrodynamic formulation. In the presence of ions, the density balance changes, and the electromagnetic wave (with frequency lower than the ion cyclotron frequency) is shown to couple with electrostatic ion mode under certain conditions. For such low frequency waves, it is also seen that the contribution of electron and positron degeneracy pressure is dominant as compared to their diffraction effects. The results are analyzed numerically for illustrative purpose pointing out their relevance to the dense laboratory (e.g., super-intense laser-dense matter interactions) and astrophysical plasmas.
Analysis of the modified optical properties and band structure of GaAs1−xSbx-capped InAs/GaAs quantum dots
Authors: Ulloa J. M. , Llorens J. M. , del Moral M. , Bozkurt M. , Koenraad P. M. , Hierro A.
Published: October 2012

The origin of the modified optical properties of InAs/GaAs quantum dots (QD) capped with a thin GaAs1−xSbx layer is analyzed in terms of the band structure. To do so, the size, shape, and composition of the QDs and capping layer are determined through cross-sectional scanning tunnelling microscopy and used as input parameters in an 8 × 8 k·p model. As the Sb content is increased, there are two competing effects determining carrier confinement and the oscillator strength: the increased QD height and reduced strain on one side and the reduced QD-capping layer valence band offset on the other. Nevertheless, the observed evolution of the photoluminescence (PL) intensity with Sb cannot be explained in terms of the oscillator strength between ground states, which decreases dramatically for Sb > 16%, where the band alignment becomes type II with the hole wavefunction localized outside the QD in the capping layer. Contrary to this behaviour, the PL intensity in the type II QDs is similar (at 15 K) or even larger (at room temperature) than in the type I Sb-free reference QDs. This indicates that the PL efficiency is dominated by carrier dynamics, which is altered by the presence of the GaAsSb capping layer. In particular, the presence of Sb leads to an enhanced PL thermal stability. From the comparison between the activation energies for thermal quenching of the PL and the modelled band structure, the main carrier escape mechanisms are suggested. In standard GaAs-capped QDs, escape of both electrons and holes to the GaAs barrier is the main PL quenching mechanism. For small-moderate Sb (<16%) for which the type I band alignment is kept, electrons escape to the GaAs barrier and holes escape to the GaAsSb capping layer, where redistribution and retraping processes can take place. For Sb contents above 16% (type-II region), holes remain in the GaAsSb layer and the escape of electrons from the QD to the GaAs barrier is most likely the dominant PL quenching mechanism. This means that electrons and holes behave dynamically as uncorrelated pairs in both the type-I and type-II structures.
Contribution of both the upperside and the underside of the wing on the iridescence in the male butterfly Troïdes magellanus (Papilionidae)
Authors: Van Hooijdonk Eloise , Berthier Serge , Vigneron Jean-Pol
Published: October 2012

Until now, the existing literature suggests that the color effects on the butterflies wings come from the scales exposed to an outside observer. The particularity of the present work lies in the consideration of both sides of a wing. The male Troïdes magellanus concentrates on its hindwings distinct but complementary optical effects contributing to its exceptional visual attraction: (i) a uniform yellow coloration under daylight, (ii) a bright glint showing bluish or greenish hues under grazing illumination and observation, and (iii) the presence of fluorescent molecules, producing a yellow-green coloration when irradiated by ultraviolet light, embedded in a three-dimensional photonic structure. Our experimental examination reveals a decomposition of the visual aspect in terms of a pigmentary, a structural, and a fluorescent component, as well as a contribution of the scales of the upperside and the underside of the wing on this observation. Our results highlight the role of the scales photonic structure—from both sides of the organ—on this correlation. The investigation was realized by means of spectrophotometric measurements, bidirectional reflectance distribution function mapping, and electron microscopy. Analyzing the scattered light according to the observation direction proved to be crucial in this work.
Comparison of some dispersion-corrected and traditional functionals with CCSD(T) and MP2 ab initio methods: Dispersion, induction, and basis set superposition error
Authors: Roy Dipankar , Marianski Mateusz , Maitra Neepa T. , Dannenberg J. J.
Published: October 2012

We compare dispersion and induction interactions for noble gas dimers and for Ne, methane, and 2-butyne with HF and LiF using a variety of functionals (including some specifically parameterized to evaluate dispersion interactions) with ab initio methods including CCSD(T) and MP2. We see that inductive interactions tend to enhance dispersion and may be accompanied by charge-transfer. We show that the functionals do not generally follow the expected trends in interaction energies, basis set superposition errors (BSSE), and interaction distances as a function of basis set size. The functionals parameterized to treat dispersion interactions often overestimate these interactions, sometimes by quite a lot, when compared to higher level calculations. Which functionals work best depends upon the examples chosen. The B3LYP and X3LYP functionals, which do not describe pure dispersion interactions, appear to describe dispersion mixed with induction about as accurately as those parametrized to treat dispersion. We observed significant differences in high-level wavefunction calculations in a basis set larger than those used to generate the structures in many of the databases. We discuss the implications for highly parameterized functionals based on these databases, as well as the use of simple potential energy for fitting the parameters rather than experimentally determinable thermodynamic state functions that involve consideration of vibrational states.
On the determination of the glass forming ability of AlxZr1−x alloys using molecular dynamics, Monte Carlo simulations, and classical thermodynamics
Authors: Harvey Jean-Philippe , Gheribi Aïmen E. , Chartrand Patrice
Published: October 2012

In this work, the glass forming ability of Al-Zr alloys is quantified using Monte Carlo (MC) and molecular dynamic (MD) simulations as well as classical thermodynamic calculations. The total energy of each studied structure of the Al-Zr system is described using the modified embedded atom model in the second-nearest-neighbour formalism. The parameterized Al-Zr cross potential which has been extensively validated using available experimental and ab initio data for several solid structures and for the liquid phase is used to evaluate thermodynamic, structural, and physical properties of the glass state and of the fully disordered (FD) face-centered cubic (FCC) solid solution with no short range order (SRO). The local environment of the Al-Zr amorphous phase is identified to be similar to that of a FCC solid structure with short range chemical order. A new approach to model the Gibbs energy of the amorphous phase based on the cluster variation method in the tetrahedron approximation is presented. The Gibbs energy of the fully disordered FCC solid solution with no short range order is determined and compared to the Gibbs energy of the amorphous phase. According to our volumetric and energetic criteria defined in our work to evaluate the possible formation of a glass structure at room temperature and zero pressure, a glass forming range of (0.25≤XZr≤0.75) and of (0.21≤XZr≤0.75) are identified, respectively. All the available quantitative experimental data regarding the amorphization of Al-Zr alloys are compared to the prediction of our MD/MC simulations throughout this study.
Comment on “Broadening of metal-oxide-semiconductor admittance characteristics: Measurement, sources, and its effects on interface state density analyses” [J. Appl. Phys. 110, 114115 (2011)]
Authors: Basile A. F. , Mooney P. M.
Published: October 2012

Low-temperature capacitance-voltage (C-V) characteristics of n-type In0.53Ga0.47As metal-oxide-semiconductor (MOS) capacitors, presented by Paterson et al. [J. Appl. Phys. 110, 114115 (2011)], are modeled by analytical and numerical calculations of the capacitance taking into account the slow response of neutral donors and interface traps to the measurement test signal. This model provides an explanation for the absence of the dip near flat band in the high frequency C-V characteristics, contrary to the prediction based on the ideal MOS capacitance. These calculations also show that a broad energy distribution of interface-traps can explain the broadening of the C-V curve.
Direct imaging and spectral identification of the interfaces in organic semiconductor-ferromagnet heterojunction
Authors: Wei D. H. , Wang Chia-Hao , Chang Hui-Ching , Chan Yuet-Loy , Lee Chih-Hao , Hsu Yao-Jane
Published: October 2012

Using x-ray spectromicroscopy, we studied the interface of pentacene (Pn)-cobalt (Co) heterojunction fabricated by thermal evaporation in an ultra-high vacuum environment. Through element-specific images and absorption spectroscopic analysis, we found evidences suggesting that part of the Co top layer penetrates into Pn film and hybridizes with molecules. As the Curie temperature of infiltrated Co clusters is dimension sensitive, the Co penetration would create an ill-defined interfacial region whose magnetization depends on the temperature and depth of cobalt penetration. The magnetic complexity at Pn/Co interface was found reduced after inserting a thin Cu layer between Pn and Co.
Nanocluster Si sensitized Er luminescence: Excitation mechanisms and critical factors for population inversion
Authors: Yong Kim In , Joong Kim Kyung , Shin Jung H.
Published: October 2012

Luminescence from Er3+ ions sensitized by nanocluster Si is investigated using finite-element, Monte-Carlo simulations. We find that we can reproduce and explain many conflicting results that have been reported using only a simple Förster-type interaction. In particular, we show that Er-Er energy migration plays a major role in Er3+ excitation such quantities such as excitation distance and sensitized fraction depend on optically active Er fraction and pumping power. Based on simulation results, we identify optically active fraction as the critical factor and suggest a multi-layered structure as being ideal for achieving population inversion.
Gold nanoparticle formation in diamond-like carbon using two different methods: Gold ion implantation and co-deposition of gold and carbon
Authors: Salvadori M. C. , Teixeira F. S. , Araújo W. W. R. , Sgubin L. G. , Spirin R. E. , Cattani M. , Brown I. G.
Published: October 2012

We describe work in which gold nanoparticles were formed in diamond-like carbon (DLC), thereby generating a Au-DLC nanocomposite. A high-quality, hydrogen-free DLC thin film was formed by filtered vacuum arc plasma deposition, into which gold nanoparticles were introduced using two different methods. The first method was gold ion implantation into the DLC film at a number of decreasing ion energies, distributing the gold over a controllable depth range within the DLC. The second method was co-deposition of gold and carbon, using two separate vacuum arc plasma guns with suitably interleaved repetitive pulsing. Transmission electron microscope images show that the size of the gold nanoparticles obtained by ion implantation is 3–5 nm. For the Au-DLC composite obtained by co-deposition, there were two different nanoparticle sizes, most about 2 nm with some 6–7 nm. Raman spectroscopy indicates that the implanted sample contains a smaller fraction of sp3 bonding for the DLC, demonstrating that some sp3 bonds are destroyed by the gold implantation.
Role of native defects in nitrogen flux dependent carrier concentration of InN films grown by molecular beam epitaxy
Authors: Tangi Malleswararao , Kuyyalil Jithesh , Shivaprasad S. M.
Published: October 2012

We address the carrier concentration, strain, and bandgap issue of InN films grown on c-sapphire at different N-flux by molecular beam epitaxy using x-ray diffraction and x-ray photoelectron spectroscopy. We demonstrate that the strain in InN films arises due to point defects like nitrogen interstitials and nitrogen antisites. We report minimal biaxial strain due to relaxed growth morphology and a minimal hydrostatic strain arising due to interstitial nitrogen atoms being partially compensated by nitrogen antisites. We find that the variation in absorption edge can be attributed to defect induced carrier concentration and that nitrogen interstitials and nitrogen antisites act as donors that yield the respective absorption edge and Moss-Burstein shift. Our studies are a step towards the ability to form low carrier concentration strain-relaxed films and to determine the intrinsic band gap value for this technologically important material.
Controlled spatial switching and routing of surface plasmons in designed single-crystalline gold nanostructures
Authors: Könenkamp R. , Word R. C. , Fitzgerald J. P. S. , Nadarajah Athavan , Saliba S. D.
Published: October 2012

Electron emission microscopy is used to visualize plasmonic routing in gold nano-structures. We show that in single-crystalline gold structures reliable routing can be achieved with polarization switching. The routing is due to the polarization dependence of the photon-to-plasmon coupling, which controls the mode distribution in the plasmonic gold film. We use specifically designed, single-crystalline planar structures. In these structures, the plasmon propagation length is sufficiently large such that significant plasmon power can be delivered to the near-field region around the end tips of the router. Solid state devices based on internal electron excitation and emission processes appear feasible.
ELMy H-mode linear simulation with 3-field model on experimental advanced superconducting tokamak using BOUT++
Authors: Liu Z. X. , Xia T. Y. , Xu X. Q. , Gao X. , Hughes J. W. , Liu S. C. , Ding S. Y. , Li J. G.
Published: October 2012

H-mode plasmas with ELM (edge localized mode) have been realized on experimental advanced superconducting tokamak (EAST) with 2.45 GHz low hybrid wave at PLHW∼1 MW in 2010. Data from EAST experiments including magnetic geometry, measured pressure profiles, and calculated current profiles are used to investigate the physics of ELM utilizing the BOUT++ code. Results from linear simulations show that the ELMs in EAST are dominated by resistive ballooning modes. When the Lundquist number (dimensionless ratio of the resistive diffusion time to the Alfvén time) is equal to or less than 107, the resistive ballooning modes are found to become unstable in the ELMy H-mode plasma. For a fixed pedestal pressure profile, increasing plasma current generates more activities of low-n ELMs.
Solution-processed dye-sensitized ZnO phototransistors with extremely high photoresponsivity
Authors: Pattanasattayavong Pichaya , Rossbauer Stephan , Thomas Stuart , Labram John G. , Snaith Henry J. , Anthopoulos Thomas D.
Published: October 2012

We report the fabrication of light-sensing thin-film transistors based on solution processed films of ZnO, as the channel material, functionalized with an organic dye as the light sensitizer. Due to the presence of the dye, the hybrid devices show exceptionally high photosensitivity to green light of 106 and a maximum photoresponsivity on the order of 104 A/W. The high performance is argued to be the result of the grain barrier limited nature of electron transport across the polycrystalline ZnO film and its dependence on charge carrier density upon illumination with green light. In addition to the excellent photoresponsivity and signal gain, the hybrid ZnO-dye photoactive layer exhibits high optical transparency. The unique combination of simple device fabrication and distinctive physical characteristics, such as optical transparency, renders the technology attractive for application in large-area transparent photodetectors.
Detection of pulsed far-infrared and terahertz light with an atomic force microscope
Authors: Ortega J.-M. , Glotin F. , Prazeres R. , Berthet J.-P. , Dazzi A.
Published: October 2012

We show that a commercial atomic force microscope can be used at room temperature as a detector throughout the infrared spectrum simply by recording the induced oscillation of its cantilever after irradiation by a pulsed laser. The oscillation amplitude can be made larger by spraying an absorbing graphite layer on the tip side. We demonstrate that its good sensitivity is due to a bilayer effect: their different thermal expansion coefficient forcing them to bend under irradiation. For the far-infrared spectral range, this device avoids the use of Helium cooled detectors and their numerous constraints.
Room temperature terahertz polariton emitter
Authors: Geiser Markus , Scalari Giacomo , Castellano Fabrizio , Beck Mattias , Faist Jérôme
Published: October 2012

Terahertz (THz) range electroluminescence from intersubband polariton states is observed in the ultra strong coupling regime, where the interaction energy between the collective excitation of a dense electron gas and a photonic mode is a significant portion of the uncoupled excitation energy. The polariton's increased emission efficiency along with a parabolic electron confinement potential allows operation up to room temperature in a nonresonant pumping scheme. This observation of room temperature electroluminescence of an intersubband device in the THz range is a promising proof of concept for more powerful THz sources.
Constrained model predictive control of proton exchange membrane fuel cell based on a combined empirical and mechanistic model
Authors: Lu Jun , Zahedi Ahmad
Published: October 2012

The modelling and control of proton exchange membrane fuel cell (PEMFC) possess great challenges due to PEMFC system's inherent nonlinearities, time-varying characteristics, and tight operating constraints. In this paper, a constrained model predictive control (MPC) strategy is designed based on a combined empirical and mechanistic model of PEMFC. First, we propose a hybrid modelling approach based on the combination of prior knowledge, under the form of the mechanistic submodel, with the empirical submodel devoted to the extraction of knowledge from operating data. The empirical submodel is a support vector machine (SVM) model, which predicts the voltage at different stack currents and temperatures under the reference hydrogen and oxygen partial pressure. The mechanistic submodel calculates the correction voltage by taking account of hydrogen and oxygen partial pressure changes. To prevent reactant starvation and excessive pressure difference across the membrane, dynamic constraints are then designed for the constrained MPC of PEMFC. The standard particle swarm optimization algorithm is modified to solve the resulting constrained optimization problem formulated by the constrained MPC. Simulation results demonstrate that the proposed method can deal with the constraints and achieve satisfactory performance.
Analysis of the mode composition of an X-band overmoded O-type Cerenkov high-power microwave oscillator
Authors: Zhang Dian , Zhang Jun , Zhong Huihuang , Jin Zhenxing
Published: October 2012

Overmoded slow wave structures (SWSs) with large diameter are utilized in O-type Cerenkov high-power microwave (HPM) sources for their high power capacity. However, multi-modes may be output simultaneously in the overmoded O-type Cerenkov HPM sources. In order to achieve high mode purity, the mode composition of the output power should be analyzed quantitatively when the structure of this type of device is being optimized. Two accurate numerical methods of making quantitative analysis of the mode composition in particle-in-cell model are introduced in this paper. And then, the mode composition of an X-band O-type Cerenkov oscillator with overmoded SWSs (D/λ ≈ 2.7) is analyzed. The analysis indicates that appropriate selection of the parameters of overmoded SWSs and electron beam is important, as mentioned in previous reports, for realizing mode selection in beam-wave interaction. Besides, designing of the mode conversion effect, which is rarely discussed, can also affect the mode purity of output power. After adjustment of the dimensions of the tapered waveguide, which converts the combination of “surface wave” and “volume wave” to the “volume wave” in the output waveguide, the percentage of total output microwave power carried by the TM01 mode is higher than 95% in the X-band overmoded Cerenkov oscillator at the diode voltage ranging from 570 kV to 750 kV.