bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Children’s Value Structures and Value Preferences
Authors: Bilsky Wolfgang , Döring Anna K. , van Beeck Franka , Rose Isabel , Schmitz Johanna , Aryus Katrin , Drögekamp Lisa , Sindermann Jeannette
Published: June 2013

Contrary to those of adults and adolescents, children’s value structures and value preferences have rarely been investigated. This paper bridges this gap by building on Schwartz’s (1992 ) value theory. We present two studies: one in which children from Germany, Portugal, and Chile, aged 10 to 12 years, completed the Portrait Values Questionnaire ( Schwartz et al., 2001 ); and one in which children from Germany and France, aged 7 to 12 years, completed the Picture-Based Value Survey for Children ( Döring, Blauensteiner, Aryus, Drögekamp, & Bilsky, 2010 ). Theory-based multidimensional scaling analyses revealed differentiated value structures in both studies. Findings on children’s value preferences converged with evidence from adult samples ( Schwartz & Bardi, 2001 ). The results are discussed in light of the present state of knowledge and consequences for future research.
The German Psychological Need Satisfaction in Exercise Scale
Authors: Rackow Pamela , Scholz Urte , Hornung Rainer
Published: June 2013

Self-determination theory (SDT) has become an established framework for exploring motivational processes in physical exercise. The integral components of SDT are three basic psychological needs. For our study we translated and validated a German scale that measures need satisfaction in exercise. A total of 614 individuals (n = 347 female, age: M = 38.39 years, SD = 12.05) recruited from a private fitness center, various sport clubs, and the Academic Sports Association Zurich, Switzerland, took part in the online-based baseline assessment (T1). Nine months later, 216 participants completed the online follow-up questionnaire (T2). The results demonstrate adequate factor validity and internal consistency at both measurement points. Moreover, construct validity was demonstrated by medium to strong correlations of several motives to exercise and the self-efficacy of physical exercise. In addition, the three subscales were differentially predictive for different types of motivation (for example, intrinsic and extrinsic) at T2, indicating good criterion validity. The newly developed German scale is a reliable and valid instrument for assessing need satisfaction in the context of physical exercise and predicting motivation over time.
Psychometric Properties and Validity of the Dyadic Coping Inventory in Portuguese
Authors: Vedes Ana , Nussbeck Fridtjof W. , Bodenmann Guy , Lind Wolfgang , Ferreira Ana
Published: June 2013

Several studies have shown that dyadic coping, that is, the way couples cope with stress, plays a unique role in intimate relationships. The aim of this study is to validate the Portuguese version of the Dyadic Coping Inventory (DCI; Bodenmann, 2008 ) by analyzing the factorial structure and psychometric properties of the DCI as well as its convergent and criterion validity. A multigroup confirmatory factor analysis was conducted in a community sample of 605 participants living in Portugal who had been in a close relationship for at least 2 years. The findings support the hypothesized five-factor structure for the DCI and self- and other-perception, and a two-factor structure for joint dyadic coping. The psychometric properties of the DCI and its criterion validity with other relationship measures (RAS and B-SRQ) were good. These results add an important contribution to the determination of the criterion validity of the DCI with measures of other crucial domains of couples’ functioning (Shared Meaning, Conflict Processes, and Quality of Sexuality, Passion, and Romance); to the cross-cultural validation of the DCI; and to the demonstration that negative DC has a significant effect on intimate relationship processes, which contradicts the findings of previous studies. Moreover, it provides an additional tool for working with Portuguese-speaking individuals all over the world.
Alltagswirksamkeit kognitiver Verhaltenstherapie bei Kindern und Jugendlichen mit Angststörungen in einer Ausbildungsambulanz
Authors: Goletz Hildegard , Yang Young-Im , Suhr-Dachs Lydia , Walter Daniel , Döpfner Manfred
Published: June 2013

Hintergrund: Bislang haben wenige Studien die Übertragbarkeit der in randomisiert-kontrollierten Studien aufgezeigten Wirksamkeit kognitiver Verhaltenstherapie bei juvenilen Angststörungen in die klinische Praxis überprüft. Vorliegende Studie untersucht die Alltagswirksamkeit kognitiver Verhaltenstherapie bei juvenilen Angststörungen in einer Ausbildungsambulanz. Methodik: In einer universitären kinder- und jugendlichenpsychotherapeutischen Ausbildungsambulanz wurden für n = 92 Kinder und Jugendliche, deren Elternbeurteilungsbögen vorlagen, und für n = 61 Jugendliche, deren Selbstbeurteilungsbögen vorlagen, die Veränderungen ihrer Angst und komorbiden Symptomatik nach kognitiver Verhaltenstherapie untersucht. Prä/Post-Mittelwertvergleiche und -Effektstärken sowie die klinische Relevanz der Symptomveränderungen wurden geprüft. Ergebnisse: Bezüglich der Angstsymptomatik insgesamt lagen die Effektstärken bei 0.81 im Fremdurteil und bei 0.79 im Selbsturteil. Die Effektstärken hinsichtlich komorbider Symptomatik variierten zwischen 0.37 und 0.84 (Fremdurteil) und zwischen 0.21 und 0.62 (Selbsturteil). 55.1 % der Kinder und Jugendlichen (Elternurteil) und 65.7 % der Jugendlichen (Selbsturteil) erzielten klinisch signifikante Verbesserungen der Angstsymptomatik. Bei mehr als 50 % der Kinder und Jugendlichen ergaben sich klinisch signifikante Verbesserungen komorbider Symptomatik. Schlussfolgerungen: Im verhaltenstherapeutischen Behandlungsverlauf juveniler Angststörungen in einer Ausbildungsambulanz lassen sich deutliche Verminderungen der Angst- und komorbiden Symptomatik nachweisen. Die Effektstärken der Angstsymptomatik insgesamt sind vergleichbar zu den Effektstärken in randomisiert-kontrollierten Studien. Die klinisch signifikanten Verbesserungen zeigten sich als vergleichbar hoch wie die Remissionsrate der Angstsymptomatik in randomisiert-kontrollierten Studien.
Psychometrische Eigenschaften des Fragebogens zur Errötungsangst (FEA)
Authors: Härtling Samia , Bögels Susan M. , Klotsche Jens , Hoyer Jürgen
Published: June 2013

Der Fragebogen zur Errötungsangst (FEA) erfasst subjektiv wahrgenommenes Erröten und die Angst davor auf sieben nach klinischen Gesichtspunkten definierten Subskalen. Die psychometrischen Gütekriterienbestimmung erfolgte in drei Stichproben: 260 Studenten, 62 Errötungsängstliche und 71 Patienten mit Sozialer Angststörung mit Errötungsangst. Zur Konstruktvalidierung wurden die Variablen Soziale Ängstlichkeit, psychopathologische Symptombelastung, Selbstwert und Persönlichkeitsfaktoren erfasst. Die Subskalen wiesen überwiegend niedrige Skaleninterkorrelationen auf. Die interne Konsistenz war mit Ausnahme zweier Skalen zufrieden stellend (Cronbachs α ≥ .74), die Retest-Reliabilität mit einer Ausnahme gut (rtt ≥ .77). Die Konstruktvalidität variierte abhängig von den betrachteten Subskalen. Veränderungen durch Psychotherapie wurden sensitiv abgebildet. Studentische und klinische Stichproben konnten mittels Diskriminanzanalyse zu 90 % korrekt zugeordnet werden. Mittels ROC-Analyse wurde für die Subskala Errötungsangst ein Schwellenwert von 3.6 ermittelt. Angesichts guter psychometrischer Eigenschaften der Subskala Errötungsangst und gleichzeitiger Einschränkungen bei der Validierung einiger Teilskalen, wird je nach Verwendungszweck der Einsatz des FEA als Kurz- oder Langform vorgeschlagen.
Scientist-practitioner gap in Deutschland: Eine empirische Studie am Beispiel psychologischer Testverfahren
Authors: Benit Nils , Soellner Renate
Published: June 2013

Obwohl Intelligenz- und Persönlichkeitstests berufliche Erfolgskriterien valide vorherzusagen vermögen ( Schmidt & Hunter, 1998 ), fristen psychologische Testverfahren in der Personalpraxis ein Schattendasein ( Schuler, Hell, Trapmann, Schaar & Boramir, 2007 ). Der vorliegende Beitrag unternimmt den Versuch, die Diskrepanz zwischen wissenschaftlich generiertem Wissen und dessen Umsetzung in der Unternehmenspraxis am Beispiel vom Einsatz psychologischer Testverfahren für die Personalauswahl zu erkunden. Neben der Verwendungshäufigkeit psychologischer Testverfahren wurden deren Validität sowie potenzielle Beweggründe gegen ihren Einsatz von Personalverantwortlichen aus 116 deutschen Unternehmen eingeschätzt. Die Ergebnisse zeigen, dass psychologische Testverfahren verhältnismäßig selten eingesetzt und nur selten von psychologischen Testverlagen bezogen werden. Eine geringe berufliche Augenscheinvalidität wurde von den Personalverantwortlichen als potentiell bedeutsamster Grund für deren geringe Verbreitung in der Unternehmenspraxis angeführt. Mittels einer Datenbankrecherche wurde daraufhin untersucht, inwiefern Praktikermagazine zum Thema Human Resources über psychologische Testverfahren informieren. Es findet sich in diesen Zeitschriften eine geringere Thematisierungsrate als in wissenschaftlichen Fachzeitschriften und damit ein unzureichender Transfer wissenschaftlicher Befunde.
Video Games for Children and Adolescents With Special Educational Needs
Authors: Durkin Kevin , Boyle James , Hunter Simon , Conti-Ramsden Gina
Published: June 2013

Almost all children play video games at some point and many play regularly. Not only are games ubiquitous in children’s leisure environments but the motivational and skill-enhancing potentialities of this technology are being exploited increasingly in education. Good quality games, which are challenging, instructive, and absorbing, can make learning enjoyable and effective. But is this the case for children who struggle in school? This paper reviews the emerging literature on video game uses by children with special educational needs. With reference to both entertainment games and “serious” games, we consider (i) the implications of developmental and learning disabilities for game play, (ii) the potential of games to address special cognitive and educational needs, and (iii) the social potential of game play. Gaps in current knowledge are identified and directions for future research are outlined.
The Effect of Cell Size and Channel Density on Neuronal Information Encoding and Energy Efficiency
Authors: Sengupta Biswa , Faisal A Aldo , Laughlin Simon B , Niven Jeremy E
Published: June 2013

Identifying the determinants of neuronal energy consumption and their relationship to information coding is critical to understanding neuronal function and evolution. Three of the main determinants are cell size, ion channel density, and stimulus statistics. Here we investigate their impact on neuronal energy consumption and information coding by comparing single-compartment spiking neuron models of different sizes with different densities of stochastic voltage-gated Na+ and K+ channels and different statistics of synaptic inputs. The largest compartments have the highest information rates but the lowest energy efficiency for a given voltage-gated ion channel density, and the highest signaling efficiency (bits spike −1) for a given firing rate. For a given cell size, our models revealed that the ion channel density that maximizes energy efficiency is lower than that maximizing information rate. Low rates of small synaptic inputs improve energy efficiency but the highest information rates occur with higher rates and larger inputs. These relationships produce a Law of Diminishing Returns that penalizes costly excess information coding capacity, promoting the reduction of cell size, channel density, and input stimuli to the minimum possible, suggesting that the trade-off between energy and information has influenced all aspects of neuronal anatomy and physiology.
An Approach for Identifiability of Population Pharmacokinetic–Pharmacodynamic Models
Authors: Shivva V , Korell J , Tucker IG , Duffull SB
Published: June 2013

Mathematical models are routinely used in clinical pharmacology to study the pharmacokinetic and pharmacodynamic properties of a drug in the body. Identifiability of these models is an important requirement for the success of these clinical studies. Identifiability is classified into two types, structural identifiability related to the structure of the mathematical model and deterministic identifiability which is related to the study design. There are existing approaches for assessment of structural identifiability of fixed‐effects models, although their use appears uncommon in the literature. In this study, we develop an informal unified approach for simultaneous assessment of structural and deterministic identifiability for fixed and mixed‐effects pharmacokinetic or pharmacokinetic–pharmacodynamic models. This approach uses an information theoretic framework. The method is applied both to simple examples to explore known identifiability properties and to a more complex example to illustrate its utility.

CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e49; doi:10.1038/psp.2013.25; advance online publication 19 June 2013
Phase transition in porous electrodes. III. For the case of a two component electrolyte
Authors: Kiyohara Kenji , Shioyama Hiroshi , Sugino Takushi , Asaka Kinji , Soneda Yasushi , Imoto Kiyoaki , Kodama Masaya
Published: June 2013

The electrochemical thermodynamics of electrolytes in porous electrodes is qualitatively different from that in the bulk with planar electrodes when the pore size is comparable to the size of the electrolyte ions. In this paper, we discuss the thermodynamics of a two component electrolyte in a porous electrode by using Monte Carlo simulation. We show that electrolyte ions are selectively adsorbed in porous electrodes and the relative concentration of the two components significantly changes as a function of the applied voltage and the pore size. This selectivity is observed not only for the counterions but also for the coions.
The photoelectron angular distribution of water clusters
Authors: Zhang Chaofan , Andersson Tomas , Förstel Marko , Mucke Melanie , Arion Tiberiu , Tchaplyguine Maxim , Björneholm Olle , Hergenhahn Uwe
Published: June 2013

The angular distribution of photoelectrons emitted from water clusters has been measured by linearly polarized synchrotron radiation of 40 and 60 eV photon energy. Results are given for the three outermost valence orbitals. The emission patterns are found more isotropic than for isolated molecules. While a simple scattering model is able to explain most of the deviation from molecular behavior, some of our data also suggest an intrinsic change of the angular distribution parameter. The angular distribution function was mapped by rotating the axis of linear polarization of the synchrotron radiation.
Critical behavior of self-assembled rigid rods on two-dimensional lattices: Bethe-Peierls approximation and Monte Carlo simulations
Authors: López L. G. , Linares D. H. , Ramirez-Pastor A. J. , Stariolo D. A. , Cannas S. A.
Published: June 2013

The critical behavior of adsorbed monomers that reversibly polymerize into linear chains with restricted orientations relative to the substrate has been studied. In the model considered here, which is known as self-assembled rigid rods (SARRs) model, the surface is represented by a two-dimensional lattice and a continuous orientational transition occurs as a function of temperature and coverage. The phase diagrams were obtained for the square, triangular, and honeycomb lattices by means of Monte Carlo simulations and finite-size scaling analysis. The numerical results were compared with Bethe-Peierls analytical predictions about the orientational transition for the square and triangular lattices. The analysis of the phase diagrams, along with the behavior of the critical average rod lengths, showed that the critical properties of the model do not depend on the structure of the lattice at low temperatures (coverage), revealing a quasi-one-dimensional behavior in this regime. Finally, the universality class of the SARRs model, which has been subject of controversy, has been revisited.
Theoretical explanation of the low-lying ν6 vibrational fundamental of the FSO3 radical by the linear vibronic coupling approach
Authors: Uhlíková Tereza , Urban Štěpán
Published: June 2013

The first attempt for a theoretical explanation of the ν6 fundamental energy levels of the fluorosulfate radical (FSO3) electronic ground state has been made. The vibronic interaction of the two lowest electronic states of the radical (\documentclass[12pt]{minimal}\begin{document}$\tilde{X}$\end{document}X̃ 2A2 and \documentclass[12pt]{minimal}\begin{document}$\tilde{A}$\end{document}Ã 2E) has been taken into consideration in the basis of the linear vibronic coupling (LVC) approximation. The strengths of the intrastate and interstate vibronic couplings have been calculated within the framework of the Köppel, Domcke, and Cederbaum (KDC) model Hamiltonian. Already this simple KDC-LVC model provides the ν6 fundamental energy, which is in very good agreement with the experimental results. From the inclusion of vibronic interactions such as the pseudo-Jahn-Teller and Jahn-Teller effects into the calculation of the fundamental energy of the ν6 mode, it can be said that mainly the interstate coupling with the electronic excited state E causes the unexpectedly low fundamental energy ν6 of the FSO3 radical.
Ultrafast dynamics in C 1s core-excited CF4 revealed by two-dimensional resonant Auger spectroscopy
Authors: Piancastelli M. N. , Guillemin R. , Simon M. , Iwayama H. , Shigemasa E.
Published: June 2013

Following core excitation in an isolated molecule, ultrafast dissociation of one particular chemical bond can occur, where “ultrafast” is defined as taking place during the lifetime of the core hole, of the order of few femtoseconds. The signature of such phenomenon can be observed in resonant Auger spectra following core excitation. We present here an investigation of ultrafast dissociation following C 1s-to-σ* core excitation in CF4, with high-resolution resonant Auger spectroscopy. We are able to characterize final states of both the molecular ion and the \documentclass[12pt]{minimal}\begin{document}${\rm CF}_3^+$\end{document} CF 3+ fragment. We use two-dimensional (2D) maps to record resonant Auger spectra across the resonance as a function of photon energy and to characterize ultrafast dynamics. This method provides immediate visual evidence of one of the important characteristics of the study of spectral features related to molecular versus fragment ionic final states, and namely their dispersion law. In the 2D maps we are also able to identify the dissociation limit for one of the molecular final states.
Analysis of intrinsic hydrogenated amorphous silicon passivation layer growth for use in heterojunction silicon wafer solar cells by optical emission spectroscopy
Authors: Ge Jia , Ling Zhi Peng , Wong Johnson , Stangl Rolf , Aberle Armin G. , Mueller Thomas
Published: June 2013

The structure and quality of intrinsic hydrogenated amorphous silicon thin films are studied with intended use as passivation layer in heterojunction silicon wafer solar cells. The thin film layers are formed by radio-frequency parallel-plate plasma-enhanced chemical vapor deposition. While the passivation quality of the films is found to improve steadily with increasing deposition temperature, a very narrow process window in terms of pressure variation is observed. The best effective lifetime is obtained at a hydrogen to silane dilution ratio of 1 and a pressure of 66.7 Pa for the used tool configuration. Raman crystallinity and Urbach energy obtained from fitting ellipsometry data confirm that the degradation of the passivation quality outside the process window is due to a phase change into microcrystalline silicon with different growth mechanisms and an increase in bonding related defects. Film growth mechanisms are proposed to account for the observed narrow process window, which are verified by optical emission spectroscopy measurements.
Selective metallization by seeded growth on patterned gold nanoparticle arrays
Authors: Raza M. A. , Zandvliet H. J. W. , Poelsema B. , Kooij E. S.
Published: June 2013

We describe the selective metallization by electroless gold deposition on pre-patterned arrays of seed particles. In the first step, highly selective deposition of seeds (gold nanoparticles) on silicon oxide surfaces is achieved using pure water. In the second step, employing an electroless seeded growth process, the isolated nanoparticles are enlarged beyond the percolation threshold to deposit conducting metal structures. We obtain patterned gold films which exhibit macroscopic conductivity values approximately a factor of three lower than that of bulk gold. The surface morphology of the films has been characterized by scanning electron microscopy and spectroscopic ellipsometry. We discuss the different regimes as observed in morphological, electrical, and optical characterization in relation to each other. The free electron contribution to the optical spectra is analyzed in terms of the Drude model. Also, the formation of gold clusters during the growth process in the non-seeded area is described.
A sustainable energy policy for Slovenia: Considering the potential of renewables and investment costs
Authors: Obrecht M. , Denac M.
Published: June 2013

In this paper, Slovenia's current energy policy is analyzed, the potential of renewable energy sources (RES) is evaluated and examined, and new options for the development of an alternative energy policy and the transition of the Slovenian energy industry into a sustainable energy industry are proposed and cross compared. On the basis of current and future electricity consumption, the evaluated RES potentials, and calculated investment prices, options for alternative investment projects and the alternative development of a more sustainable energy policy in Slovenia are identified. These possibilities and the current energy policy are analyzed and cross-compared from the economic and environmental viewpoint, with special emphasis on investment costs. At the end of the paper, the implementation costs of the proposed alternative energy policy investments are evaluated, calculated, and cross-compared, and the advantages and disadvantages of the alternative energy policy are evaluated. The proposed alternatives have significant benefits in comparison to the existing energy strategy, which focuses on a new lignite thermal power plant. Reconstruction of the existing thermal power plant in Šoštanj is a considerably cheaper alternative and a sound transitory solution for Slovenia. Investment in a multiple fuel power plant is also a cheaper and more efficient alternative, which, in addition, enables the usage of local biomass. Another considerably cheaper and more efficient alternative with lower emissions is a gas-steam power plant. The most promising alternative is found to be electricity production from local RES, resulting in a significant reduction of energy related emissions and domestic sources usage. The estimated investment costs for the last alternative are comparable to the costs for the implementation of Slovenia's current energy policy.
Spontaneous quasi-periodic current self-oscillations in a weakly coupled GaAs/(Al,Ga)As superlattice at room temperature
Authors: Huang Yuyang , Li Wen , Ma Wenquan , Qin Hua , Grahn Holger T. , Zhang Yaohui
Published: June 2013

We have experimentally observed spontaneous quasi-periodic current self-oscillations at room temperature in a doped, weakly coupled GaAs/(Al,Ga)As superlattice (SL) with 50 periods, 7 nm well width, and 4 nm barrier width. The mole fraction of the aluminum in the barrier has been chosen to be 0.45 so that the direct barrier at the Γ point is as high as possible and thermal carrier leakage through the X valley is as small as possible. A spectral analysis of the current self-oscillations, which are observed under DC voltage bias alone, demonstrates that spontaneous quasi-periodic oscillation modes coexist with periodic ones.
Note: The influence of exploding foil shape on energy deposition
Authors: Zeng Qingxuan , Lv Junjun , Li Mingyu
Published: June 2013

The main influence factors of exploding bridge foil were studied in order to improve energy utilization of the explosion foil initiator. “Square” and “curving” shaped bridge foils were fabricated using magnetron sputtering and chemical etching techniques, and the key dimension of the bridge foil was measured using surface profiler. Commercial software MATLAB was employed to calculate the burst current, burst voltage, and energy deposition. Simulation results were in good agreement with experiment data. In this study, the energy deposition ratio of “square” shaped bridge is between 45%–50%, while the value of “curving” shaped bridge is between 55%–75%.
Relativistic nonlinear dynamics of an intense laser beam propagating in a hot electron-positron magnetoactive plasma
Authors: Sepehri Javan N. , Adli F.
Published: June 2013

The present study is devoted to investigation of the nonlinear dynamics of an intense laser beam interacting with a hot magnetized electron-positron plasma. Propagation of the intense circularly polarized laser beam along an external magnetic field is studied using a relativistic two-fluid model. A modified nonlinear Schrödinger equation is derived based on the quasi-neutral approximation, which is valid for hot plasma. Light envelope solitary waves and modulation instability are studied, for one-dimensional case. Using a three-dimensional model, spatial-temporal development of laser pulse is investigated. Occurrence of some nonlinear phenomena such as self-focusing, self-modulation, light trapping, and filamentation of laser pulse is discussed. Also the effect of external magnetic field and plasma temperature on the nonlinear evolution of these phenomena is studied.
Sheath and boundary conditions in a collisional magnetized warm electronegative plasma
Authors: Li Jing-ju , Ma J. X. , Wei Zi-an
Published: June 2013

The characteristics of a weakly collisional sheath in a warm electronegative plasma in the presence of an oblique magnetic field are investigated using a fluid model including the effects of ionization and ion-neutral collisions. The general sheath criterion imposed on the entrance velocity component of the positive ions perpendicular to the wall at the sheath-presheath edge is derived and discussed. It is shown that the boundary conditions are crucial to the sheath structure. Without including the entrance velocity components parallel to the wall, a pulse-like structure in the positive-ion density distribution near the sheath-presheath edge appears if the magnetic field is strong. With inclusion of all velocity components at the edge, the pulse-like structure disappears, resulting in a smooth sheath profile. It is also found that increasing the temperature and decreasing the concentration of the negative ions will increase the sheath thickness, and increasing the magnetic field will decrease the sheath thickness.
Strain-induced stabilization of Al functionalization in graphene oxide nanosheet for enhanced NH3 storage
Authors: Li Yunguo , De Sarkar Abir , Pathak Biswarup , Ahuja Rajeev
Published: June 2013

Strain effects on the stabilization of Al ad-atom on graphene oxide (GO) nanosheet as well as its implications for NH3 storage have been investigated using first-principles calculations. Tensile strain is found to be very effective in stabilizing the Al ad-atom on GO. It strengthens the C–O bonds through an enhanced charge transfer from C to O atoms. Interestingly, Al's stability is governed by the bond strength of C-O rather than that of Al-O. Optimally strained Al-functionalized GO binds up to 6 NH3 molecules, while it binds no NH3 molecule in unstrained condition.
Orbital stability of a two parameter family of solitary waves for a fourth order nonlinear Schrödinger type equation
Authors: Segata Jun-ichi
Published: June 2013

This paper is concerned with the orbital stability of a two parameter family of solitary waves for the fourth order nonlinear Schrödinger type equation (4NLS). By using variational approach, we prove that those solitary waves are orbitally stable under the time evolution by 4NLS.
Improved hole distribution in InGaN/GaN light-emitting diodes with graded thickness quantum barriers
Authors: Ju Z. G. , Liu W. , Zhang Z.-H. , Tan S. T. , Ji Y. , Kyaw Z. B. , Zhang X. L. , Lu S. P. , Zhang Y. P. , Zhu B. B. , Hasanov N. , Sun X. W. , Demir H. V.
Published: June 2013

InGaN/GaN light-emitting diodes (LEDs) with graded-thickness quantum barriers (GTQB) are designed and grown by metal-organic chemical-vapor deposition. The proposed GTQB structure, in which the barrier thickness decreases from the n-GaN to p-GaN side, was found to lead to an improved uniformity in the hole distribution and thus, radiative recombination rates across the active region. Consequently, the efficiency droop was reduced to 28.4% at a current density of 70 A/cm2, which is much smaller than that of the conventional equal-thickness quantum barriers (ETQB) LED, which is 48.3%. Moreover, the light output power was enhanced from 770 mW for the ETQB LEDs to 870 mW for the GTQB LEDs at 70 A/cm2.
Counting molecular-beam grown graphene layers
Authors: Plaut Annette S. , Wurstbauer Ulrich , Pinczuk Aron , Garcia Jorge M. , Pfeiffer Loren N.
Published: June 2013

We have used the ratio of the integrated intensity of graphene's Raman G peak to that of the silicon substrate's first-order optical phonon peak, accurately to determine the number of graphene layers across our molecular-beam (MB) grown graphene films. We find that these results agree well both, with those from our own exfoliated single and few-layer graphene flakes, and with the results of Koh et al. [ACS Nano 5, 269 (2011)]. We hence distinguish regions of single-, bi-, tri-, four-layer, etc., graphene, consecutively, as we scan coarsely across our MB-grown graphene. This is the first, but crucial, step to being able to grow, by such molecular-beam-techniques, a specified number of large-area graphene layers, to order.
Improved carrier injection and efficiency droop in InGaN/GaN light-emitting diodes with step-stage multiple-quantum-well structure and hole-blocking barriers
Authors: Zheng Zhiyuan , Chen Zimin , Chen Yingda , Wu Hualong , Huang Shanjin , Fan Bingfeng , Wu Zhisheng , Wang Gang , Jiang Hao
Published: June 2013

Hole transport control and carrier injection improvement have been demonstrated in the InGaN/GaN light-emitting diodes (LEDs) with step-stage multiple-quantum-well (MQW) structure and Si-doped hole-blocking barriers. Single-wavelength emission was obtained under electrical pumping in these LEDs by utilizing hole-blocking effect. The light emission around 450 nm showed a substantial increase compared with the reference sample with single or step-stage indium-content MQWs. The droop behavior and wavelength stability were also improved significantly. These improvements were attributed to the enhanced carrier injection to the active region due to the alleviation of the quantum-confined Stark effect and the effective hole-blocking effect of the Si-doped barriers.
Determination of coupling rate of light emitter to surface plasmon polaritons supported on nanohole array
Authors: Cao Z. L. , Ong H. C.
Published: June 2013

It is known that surface plasmon mediated fluorescence comprises of excitation and emission enhancements. In particular, for emission enhancement, the energy from the excited emitters is first coupled to surface plasmon polaritons (SPPs), which in turn radiatively scatter to far-field. However, these two sequential processes are rarely studied individually, making the understanding of them difficult. Here, we decouple them by using rate equation model and study the coupling as a function of emission wavelength by finite-difference time-domain simulation. As a demonstration, we measure the coupling rate of styryl 8 fluorescent dyes to SPPs on Au nanohole array in Γ-X direction.
Diffusion-induced wrinkling instability in a circular poroelastic plate
Authors: Li Kai , Ding Kewei , Cai Shengqiang
Published: June 2013

A poroelastic material can imbibe solvent and swell. When the material swells inhomogeneously or swells under external constraints, stresses can develop inside the material. The stresses can trigger mechanical instabilities in the material or even break the material, which have been often observed in experiments. In this paper, we study the wrinkling instability of a circular poroelastic plate, in the process of solvent molecules migrating into the plate from the edge. The critical conditions for the initiation and disappearance of wrinkles in the plate are presented.
Long-wavelength optical properties of a plasmonic crystal composed of end-to-end nanorod dimers
Authors: Yu X. Q. , Zhou L. , Dong Z. G. , Bai Y. F. , Zhu S. N.
Published: June 2013

We theoretically investigate the long-wavelength optical properties of a plasmonic crystal composed of end-to-end gold nanorod dimers. The strong coupling between incident light and the electron oscillations inside the nanorods gives rise to a plasmon polariton, which can be analogous to the phonon polariton in an ionic crystal. Huang-Kun-like equations are employed to explore the underlying physical mechanism for both symmetrical and asymmetrical geometries. In the long wavelength limit, the macroscopic dielectric response of the proposed structure is deduced analytically. The polariton dispersion curve shows a typical anticrossing profile in the strong coupling regime and adjacent branches are separated by a Rabi splitting. The resultant polaritonic stop band is validated by the numerical simulations.
Perceptual Organization in Colour Perception: Inverting the Gamut Expansion Effect
Authors: Ekroll Vebjørn , Faul Franz
Published: June 2013

In the well-known gamut expansion effect, uniformly coloured target patches are perceived as more colourful when they are embedded in a uniform grey surround than when they are embedded in a variegated one. Here, we provide a demonstration showing that this effect can be inverted when the uniformly coloured target patches are replaced by variegated ones. This observation suggests that the gamut expansion effect is due to mechanisms of transparency perception rather than due to contrast adaptation.
Designing an activity-based costing model for a non-admitted prisoner healthcare setting
Authors: Cai Xiao , Moore Elizabeth , McNamara Martin
Published: June 2013

Aim. To design and deliver an activity-based costing model within a non-admitted prisoner healthcare setting. Method. Key phases from the NSW Health clinical redesign methodology were utilised: diagnostic, solution design and implementation. Results. The diagnostic phase utilised a range of strategies to identify issues requiring attention in the development of the costing model. The solution design phase conceptualised distinct ‘building blocks’ of activity and cost based on the speciality of clinicians providing care. These building blocks enabled the classification of activity and comparisons of costs between similar facilities. The implementation phase validated the model. Conclusions. The project generated an activity-based costing model based on actual activity performed, gained acceptability among clinicians and managers, and provided the basis for ongoing efficiency and benchmarking efforts.
Acclimation of leaf dark respiration to nocturnal and diurnal warming in a semiarid temperate steppe
Authors: Chi Yonggang , Xu Ming , Shen Ruichang , Wan Shiqiang
Published: June 2013

A better understanding of thermal acclimation of leaf dark respiration in response to nocturnal and diurnal warming could help accurately predict the changes in carbon exchange of terrestrial ecosystems under global warming, especially under the asymmetric warming. A field manipulative experiment was established with control, nocturnal warming (1800–0600 hours), diurnal warming (0600–1800 hours), and diel warming (24 h) under naturally fluctuating conditions in a semiarid temperate steppe in northern China in April 2006. Temperature response curves of in situ leaf dark respiration for Stipa krylovii Roshev. were measured at night (Rn) and after 30 min of darkness imposed in the daytime (Rd). Leaf nonstructural carbohydrates were determined before sunrise and at sunset. Results showed that Rn could acclimate to nocturnal warming and diurnal warming, but Rd could not. The decreases in Q10 (temperature sensitivity) of Rn under nocturnal-warming and diurnal warming regimes might be attributed to greater depletion of total nonstructural carbohydrates (TNC). The real-time and intertwined metabolic interactions between chloroplastic and mitochondrial metabolism in the daytime could affect the impacts of warming on metabolite pools and the distinct response of Rn and Rd to warming. Projection on climate change–carbon feedback under climate warming must account for thermal acclimation of leaf dark respiration separately by Rn and Rd.
Structural similarity of wild-type and ALS-mutant superoxide dismutase-1 fibrils using limited proteolysis and atomic force microscopy
Authors: Chan Pik K. , Chattopadhyay Madhuri , Sharma Shivani , Souda Puneet , Gralla Edith Butler , Borchelt David R. , Whitelegge Julian P. , Valentine Joan Selverstone
Published: June 2013

Abnormal assemblies formed by misfolded superoxide dismutase-1 (SOD1) proteins are the likely cause of SOD1-linked familial amyotrophic lateral sclerosis (fALS) and may be involved in some cases of sporadic ALS. To analyze the structure of the insoluble SOD1 amyloid fibrils, we first used limited proteolysis followed by mass spectrometric analysis. Digestion of amyloid fibrils formed from full-length N-acetylated WT SOD1 with trypsin, chymotrypsin, or Pronase revealed that the first 63 residues of the N terminus were protected from protease digestion by fibril formation. Furthermore, every tested ALS-mutant SOD1 protein (G37R, L38V, G41D, G93A, G93S, and D101N) showed a similar protected fragment after trypsin digestion. Our second approach to structural characterization used atomic force microscopy to image the SOD1 fibrils and revealed that WT and mutants showed similar twisted morphologies. WT fibrils had a consistent average helical pitch distance of 62.1 nm. The ALS-mutant SOD1 proteins L38V, G93A, and G93S formed fibrils with helical twist patterns very similar to those of WT, whereas small but significant structural deviations were observed for the mutant proteins G37R, G41D, and D101N. Overall, our studies suggest that human WT SOD1 and ALS-mutants tested have a common intrinsic propensity to fibrillate through the N terminus and that single amino acid substitutions can lead to changes in the helical twist pattern.
Free products in R. Thompson’s group 𝑉
Authors: Bleak Collin , Salazar-Díaz Olga
Published: June 2013

We investigate some product structures in R. Thompson’s group

V
V

, primarily by studying the topological dynamics associated with

V
V

’s action on the Cantor set

C

\mathfrak {C}

. We draw attention to the class

D

(
V
,

C

)

\mathcal {D}_{(V,\mathfrak {C})}

of groups which have embeddings as demonstrative subgroups of

V
V

whose class can be used to assist in forming various products. Note that

D

(
V
,

C

)

\mathcal {D}_{(V,\mathfrak {C})}

contains all finite groups, the free group on two generators, and

Q

/

Z

\mathbf {Q}/\mathbf {Z}

, and is closed under passing to subgroups and under taking direct products of any member by any finite member. If

G
≤
V

G\leq V

and

H
∈

D

(
V
,

C

)

H\in \mathcal {D}_{(V,\mathfrak {C})}

, then

G
≀
H

G\wr H

embeds into

V
V

. Finally, if

G
G

,

H
∈

D

(
V
,

C

)

H\in \mathcal {D}_{(V,\mathfrak {C})}

, then

G
∗
H

G*H

embeds in

V
V

.

Using a dynamical approach, we also show the perhaps surprising result that

Z
2

∗
Z

Z^2*Z

does not embed in

V
V

, even though

V
V

has many embedded copies of

Z
2

Z^2

and has many embedded copies of free products of various pairs of its subgroups.
RanGTP and CLASP1 cooperate to position the mitotic spindle
Authors: Bird Stephen L. , Heald Rebecca , Weis Karsten
Published: June 2013

Accurate positioning of the mitotic spindle is critical to ensure proper distribution of chromosomes during cell division. The small GTPase Ran, which regulates a variety of processes throughout the cell cycle, including interphase nucleocytoplasmic transport and mitotic spindle assembly, was recently shown to also control spindle alignment. Ran is required for the correct cortical localization of LGN and nuclear-mitotic apparatus protein (NuMA), proteins that generate pulling forces on astral microtubules (MTs) through cytoplasmic dynein. Here we use importazole, a small-molecule inhibitor of RanGTP/importin-β function, to study the role of Ran in spindle positioning in human cells. We find that importazole treatment results in defects in astral MT dynamics, as well as in mislocalization of LGN and NuMA, leading to misoriented spindles. Of interest, importazole-induced spindle-centering defects can be rescued by nocodazole treatment, which depolymerizes astral MTs, or by overexpression of CLASP1, which does not restore proper LGN and NuMA localization but stabilizes astral MT interactions with the cortex. Together our data suggest a model for mitotic spindle positioning in which RanGTP and CLASP1 cooperate to align the spindle along the long axis of the dividing cell.
Bottom-heavy initial mass function in a nearby compact L★ galaxy
Authors: Läsker Ronald , van den Bosch Remco C. E , van de Ven Glenn , Ferreras Ignacio , La Barbera Francesco , Vazdekis Alexandre , Falcón-Barroso Jesús
Published: June 2013

We present orbit-based dynamical models and stellar population analysis of Sloan Digital Sky Survey J151741.75−004217.6, a low-redshift (z = 0.116) early-type galaxy (ETG) which, for its moderate luminosity, has an exceptionally high velocity dispersion. We aim to determine the central black hole (BH) mass (M•), the i-band stellar mass-to-light ratio (ϒ*, i) and the slope of the initial mass function (IMF). Combining constraints from Hubble Space Telescope imaging and long-slit kinematic data with those from fitting the spectrum with stellar populations models of varying IMFs, we show that this galaxy has a large fraction of low-mass stars, significantly higher than implied even by a Salpeter IMF. We exclude a Chabrier/Kroupa as well as a unimodal (i.e. single-segment) IMF, while a bimodal (low-mass tapered) shape is consistent with the dynamical constraints. Thereby, our study demonstrates that a very bottom-heavy IMF can exist even in an L* ETG. We place an upper limit of 1010.5 M⊙ on M•, which still leaves open the possibility of an extremely massive BH.
A new rare type of supernovae: hypervelocity stellar collisions at galactic centres
Authors: Balberg Shmuel , Sari Re’em , Loeb Abraham
Published: June 2013

When a binary star system is tidally disrupted by a supermassive black hole at a galactic nucleus, one star is ejected at a high speed while the other remains in a tightly bound orbit around the black hole. The cluster of tightly bound stars builds over time, eventually creating a steady state in which the rate of collisions between these stars is similar to the rate of capturing new stars. A large fraction of the collisions occur near the periapsis of the orbits around the black hole, where the kinetic energies are sufficient to generate an explosive disruption of the two stars involved. The typical flare brightens for several days, with a peak luminosity that is comparable to the lower luminosity end of known supernovae. The explosion light curve is followed by a longer flare due to accretion of ejected matter on to the black hole. Dedicated searches in the near universe could observe several such ‘collisional supernovae’ per year.
An Analysis of ANES Items and Their Use in the Construction of Political Knowledge Scales
Authors: Pietryka Matthew T. , MacIntosh Randall C.
Published: June 2013

Valid comparisons of group scores on additive measures such as political knowledge scales require that the conditional response probabilities for individuals on the observed items be invariant across groups after controlling for their overall level of the latent trait of interest. Using a multi-group confirmatory factor analysis of knowledge items drawn from American National Election Studies, we find that the scales used in recent research are not sufficiently invariant for valid comparisons across a host of theoretically important grouping variables. We demonstrate that it is possible to construct valid invariant scales using a subset of items and show the impact of invariance by comparing results from the valid and invalid scales. We provide an analysis of differential item functioning based on grouping variables commonly used in political science research to explore the utility of each item in the construction of valid knowledge scales. An application of the VTT suggests it is more appropriate to conceive of these items as effects of a latent variable rather than cause or formative indicators. These results suggest that models attempting to explain apparent knowledge gaps between subgroups have been unsuccessful because previously constructed scales were validated by fiat.
Influence of Nitrous Oxide Anesthesia, B-Vitamins, andMTHFRGene Polymorphisms on Perioperative Cardiac Events
Authors: Nagele Peter , Brown Frank , Francis Amber , Scott Mitchell G. , Gage Brian F. , Miller J. Philip
Published: June 2013

Background:

Nitrous oxide causes an acute increase in plasma homocysteine that is more pronounced in patients with the methylenetetrahydrofolate reductase (MTHFR) C677T or A1298C gene variant. In this randomized controlled trial, the authors sought to determine whether patients carrying the MTHFR C677T or A1298C variant had a higher risk for perioperative cardiac events after nitrous oxide anesthesia and whether this risk could be mitigated by B-vitamins.

Methods:

The authors randomized adult patients with cardiac risk factors undergoing noncardiac surgery, to receive nitrous oxide plus intravenous B-vitamins before and after surgery, or to nitrous oxide and placebo. Serial cardiac biomarkers and 12-lead electrocardiograms were obtained. The primary study endpoint was the incidence of myocardial injury, as defined by cardiac troponin I increase within the first 72 h after surgery.

Results:

A total of 500 patients completed the trial. Patients who were homozygous for either MTHFR C677T, or A1298C gene variant (n = 98; 19.6%) had no increased rate of postoperative cardiac troponin I increase compared with wild-type and heterozygous patients (11.2 vs. 14.0%; relative risk 0.96; 95% CI, 0.85–1.07; P = 0.48). B-vitamins blunted the rise in homocysteine, but had no effect on cardiac troponin I increase compared with patients receiving placebo (13.2 vs. 13.6%; relative risk 1.02; 95% CI 0.78 to 1.32; P = 0.91).

Conclusions:

Neither MTHFR C677T and A1298C gene variant, nor acute homocysteine increase are associated with perioperative cardiac troponin increase after nitrous oxide anesthesia. B-vitamins blunt nitrous oxide-induced homocysteine increase but have no effect on cardiac troponin I increase.