bluuebunny/crossref_metadata_2025 huggingface dataset:
Age and growth of forkbeard, Phycis phycis, in Portuguese continental waters
Authors: Vieira Ana Rita , Neves Ana , Sequeira Vera , Paiva Rafaela Barros , Gordo Leonel Serrano
Published: December 2013

The forkbeard, Phycis phycis, is an important commercial species in Portugal; however, little information is available on its biology. Age and growth of the forkbeard from Portuguese continental waters were studied using 687 otoliths from specimens caught between May 2011 and December 2012. Otoliths were transversally sectioned, and assigned ages were validated by marginal increment analysis and edge analysis, and indices of precision were also calculated to corroborate ageing within and between readers. Validation techniques showed that an annual growth increment is formed every year, corresponding to the succession of an opaque and a translucent growth zone. Specimens ranged from 15.5 to 67.1 cm total length (TL), and their estimated ages ranged between 0 and 18 years. The forkbeard is a relatively slow growing, long lived species, that does not show sexual dimorphism in growth. The von Bertalanffy growth parameters estimated for forkbeard from the Portuguese continental waters were L∞ = 75.14 cm TL, k = 0.10 yr−1 and t0 = −2.09 yr.
Species diversity, community structure and distribution of phytoplankton in the Changjiang estuary during dry and flood periods
Authors: Guo P.Y. , Shen H.T. , Wang J.H.
Published: December 2013

This paper reports on the phytoplankton community, its composition, structure and distribution in Changjiang estuary from February 1999 to March 2000. Two hundred and eight species were identified in the dry and flood periods. Diatoms, with 143 species observed, was the most abundant phytoplankton group, accounting for 68.75% of the total phytoplankton species number. Skeletonema costatum was dominant among all the species. The phytoplankton of Changjiang estuary in China was divided into five ecological categories: freshwater species, estuary brackish water species, inshore low salinity species, inshore widespread species and off-sea high salinity species. During the dry period, the major phytoplankton populations in the surface layer were estuary inshore and offshore populations, distinguished from the composition of the bottom layer. The community structure was similar in the two layers during the flood period. The phytoplankton species diversity was calculated for Simpson, Shannon–Weaver diversity and evenness indices, and found to be higher in the dry period, due to the simple dominant species and low spatial heterogeneity in the flood period. Higher phytoplankton abundance was observed in the surface layer during the flood period. The phytoplankton species distribution, coinciding with the dominant species distribution, varied with salinity, and their abundance correlated significantly with nutrients and light.
The neuroscience of free will: implications for psychiatry
Authors: Pierre J. M.
Published: December 2013

Belief in free will has been a mainstay in philosophy throughout history, grounded in large part in our intuitive sense that we consciously control our actions and could have done otherwise. However, psychology and psychiatry have long sought to uncover mechanistic explanations for human behavior that challenge the notion of free will. In recent years, neuroscientific discoveries have produced a model of volitional behavior that is at odds with the notion of contra-causal free will and our sense of conscious agency. Volitional behavior instead appears to have antecedents in unconscious brain activity that is localizable to specific neuroanatomical structures. Updating notions of free will in favor of a continuous model of volitional self-control provides a useful paradigm to conceptualize and study some forms of psychopathology such as addiction and impulse control disorders. Similarly, thinking of specific symptoms of schizophrenia as disorders of agency may help to elucidate mechanisms of psychosis. Beyond clinical understanding and etiological research, a neuroscientific model of volitional behavior has the potential to modernize forensic notions of responsibility and criminal punishment in order to inform public policy. Ultimately, moving away from the language of free will towards the language of volitional control may result in an enhanced understanding of the very nature of ourselves.
Who Wants to Be a Communist? Career Incentives and Mobilized Loyalty in China
Authors: Dickson Bruce J.
Published: December 2013

This article analyses trends in the Chinese Communist Party's recruitment strategy and the composition of Party members. Based on original survey data, it analyses the motives for joining the CCP, the consequences on career mobility, and the effects of Party membership on political beliefs and behaviour in contemporary China. These data reveal three key findings. First, for those who aspire to positions in the Party/government bureaucracy or SOEs, Party membership is a necessary, if not sufficient, condition; for those in the non-state sector, it is youth and college education that are the keys to top jobs, and not Party membership. Second, CCP members are more likely to donate time, money, and even blood, for various causes, and to vote in local people's congress elections. This behaviour demonstrates mobilized loyalty: the CCP mobilizes its members to participate in these activities to demonstrate their loyalty to the regime and to serve as examples to the rest of the population. Third, Party members are not more likely to support and trust their state institutions: while they do have higher levels of support for the centre than the rest of population generally, Party membership does not produce increased support for the local state. Nor does economic development: all else being equal, support for central and local party-state institutions is lower in the most developed cities. These findings call into question the Party's recruitment and development policies, as well as the conventional wisdom on the link between economic development and popular support for the status quo.
Law and the Art of Defining Religion
Authors: Kenny Celia G
Published: December 2013

In the increasingly complex conjunction of law and religion, one of the most crucial questions concerns the privileged place of religion among other convictional positions which are protected under Article 9 of the European Convention on Human Rights. This article argues the need for a trans-disciplinary approach to the question of definitions, importing insights from philosophy, sociology of law and neo-pragmatism. The aim is to elucidate the view that defining is both an art (in the discursive construction of its object) and a form of politics (as a regulative technology, through which the actual flux and complexity of human reality is brought under control). The question of what religion is (the ontological question) should be acknowledged as a jurisprudential red herring.
Disability and Demonstrating Christian Commitment
Authors: Jarman Andrea Loux
Published: December 2013

Community lies at the heart of both church and school life in the Church of England. In some areas, church communities are sustained by families who choose to attend a particular church based on the quality of the church school in its parish. Many Voluntary Aided Church of England schools (church schools) give priority admission to parents on the basis of faith in the oversubscription criteria of their admission arrangements. While the Church stresses inclusiveness in its recommendations regarding admissions policies to church schools, where a church school is very popular and oversubscribed arguably priority must be given to parents of the faith in the school's catchment area. Otherwise parishioner children whose families regularly attend church could fail to be admitted to their local church school because of competition for places.
How to switch to agomelatine after an unsuccessful try with paroxetine or venlafaxine
Authors: Lejoyeux Michel , Matharan Sophie , de Bodinat Christian
Published: December 2013

Objective/introduction

The present trial informs clinicians about switching conditions with the antidepressant agomelatine after the failure of a treatment with either paroxetine or venlafaxine.

Methods

The total number of discontinuation-emergent symptoms, according to the Discontinuation-Emergent Signs and Symptoms checklist, was compared in double-blind conditions after 3 switching options: immediate substitution or initiation of agomelatine (25 mg/day p.o.) with either a short- or long-tapering of the previous drug. Secondary objectives included tolerability and safety assessments and the early clinical benefit after the switch.

Results

For all switching options, a withdrawal syndrome was observed 1 week after cessation of the selective serotonin reuptake inhibitor (SSRI)/serotonin–norepinephrine reuptake inhibitor (SNRI) treatment. Psychic symptoms were the most frequently reported, and somatic symptoms were comparatively few. Early discontinuation symptoms after cessation of SSRI/SNRI treatment did not prejudice the antidepressant benefits of agomelatine over 8 weeks.

Conclusions

Both abrupt and start–taper switching with agomelatine are options in everyday practice for those patients who have not responded to either paroxetine or venlafaxine. However, regardless of the switching strategy, the present double-blind study shows that early discontinuation symptoms that arise upon cessation of SSRI/SNRI can alter the patients’ perception of the clinical benefit of the new antidepressant. Both practitioners and patients must be warned about these early discontinuation symptoms to prevent the symptoms from being confounded with a lack of therapeutic benefit of the new treatment.
Bilingual experience modulates hemispheric lateralization in visual word processing
Authors: LAM SZE-MAN , HSIAO JANET H.
Published: December 2013

Previous studies showed reduced hemispheric asymmetry in face perception in bilinguals compared with monolinguals, suggesting that hemispheric asymmetry in visual stimulus processing may be modulated by language reading experience. Here we examined whether this phenomenon can also be observed in bilinguals with different language backgrounds. We compared English monolinguals, European–English bilinguals (who know two alphabetic languages), and Chinese–English bilinguals (who have mastered a logographic and an alphabetic language) in an English word sequential matching task. We showed that European–English bilinguals had a stronger right visual field/left hemispheric advantage than the other two groups, suggesting that different language experiences can influence how visual words are processed in the brain. In addition, by using a computational model that implements a theory of hemispheric asymmetry in perception, we showed that this lateralization difference could be accounted for by the difference in participants’ vocabulary size and the difference in word-to-sound mapping between alphabetic and logographic languages.
Compact MIMO antenna with optimized mutual coupling reduction using DGS
Authors: Ibrahim Ahmed A. , Abdalla Mahmoud A. , Abdel-Rahman Adel B. , Hamed Hesham F. A.
Published: December 2013

A design of low mutual coupling between two microstrip patch antennas for multi input multi output antenna is presented. The two antenna elements operate at 5.8 GHz for wireless applications. The reduction of mutual coupling between the antenna elements is achieved by using a defected ground structure (DGS). The DGS is inserted between the microstrip patch antenna elements to limit the surface waves between them. The separation between the edges of the two elements has been achieved to be only 0.058λ0. The analysis of the correlation coefficient, diversity gain and total active reflection coefficient is presented to validate the performance of the multiple-input–multiple-output (MIMO) antenna. The isolation of the proposed MIMO antenna is 28 dB at 5.8 GHz and the envelope correlation equals 0.003. Owing to these good performances each antenna can operate almost independently. A good agreement is achieved between the simulated and the measured results.
A new challenge or a new role? The ICRC in Northern Ireland
Authors: Loane Geoff
Published: December 2013

Despite the narrative of success surrounding the Northern Ireland peace process, which culminated in the 1998 Good Friday Agreement, there remain significant humanitarian consequences as a result of the violence. The International Committee of the Red Cross (ICRC) has opened an office in Belfast after its assessments demonstrated a need for intervention. While a two-year ‘dirty protest’ in Northern Ireland's main prison has been recently resolved, paramilitary structures execute punishments, from beatings to forced exile and even death, outside of the legal process and in violation of the criminal code. This article examines the face of modern humanitarianism outside of armed conflict, its dilemmas, and provides analysis as to why the ICRC has a role in the Northern Ireland context.
Southeast Asian Approaches to Maritime Boundaries
Authors: DAVENPORT Tara
Published: December 2013

From both a geographical and geopolitical perspective, Southeast Asia is a particularly interesting case-study for maritime delimitation. Despite the existence of significant obstacles to maritime boundary-making, including a complex coastal geography and a multitude of territorial and jurisdictional disputes, Southeast Asia has been described as the “scene of very active and innovative ocean boundary diplomacy”. The objective of this paper is to examine Southeast Asian approaches to maritime boundaries. First, it seeks to identify whether there are common trends and practices in Southeast Asian practice which have contributed to the high number of maritime boundaries concluded by Southeast Asian states. Second, the paper will explore the extent to which Southeast Asian practice has contributed to the normative development of international law on maritime delimitation. Third, the paper will discuss whether there are any lessons to be learned from Southeast Asian practice that can be used to settle unresolved maritime boundary issues in the region.
Managers' reactions towards employees' disclosure of psychiatric or somatic diagnoses
Authors: Mendel R. , Kissling W. , Reichhart T. , Bühner M. , Hamann J.
Published: December 2013

Aims.

To study whether employees who disclose a psychiatric diagnosis, such as depression risk stigmatisation and discrimination at the workplace.

Methods.

Randomised experimental study with 748 managers from German companies incorporating four case vignettes displaying an employee with different ‘diagnoses’ (depression, burnout, private crisis and thyroid dysfunction), but identical unspecific complaints. Main outcome measures were the managers' attitudes and their impact on stigmatisation with respect to job performance.

Results.

In nearly all aspects of job performance, the diagnosis depression (psychiatric disorder) was seen as more critical than the diagnosis of a thyroid dysfunction (somatic disease). The diagnosis ‘burnout’ did not prove to be less stigmatising than ‘depression’. Likewise ‘private crisis’ was rated less favourably than thyroid dysfunction.

Conclusions.

Therefore, employees have to evaluate if they disclose their psychiatric disorder or if they conceal it as a somatic illness.
Frequency tracking in acoustic trapping for improved performance stability and system surveillance
Authors: Hammarström Björn , Evander Mikael , Wahlström Jacob , Nilsson Johan
Published: December 2013

This work demonstrates an acoustic trapping system where the optimal trapping frequency is automatically determined and can be used to analyse changes in the acoustic trap.
Top-down fabrication of three-dimensional porous V2O5 hierarchical microplates with tunable porosity for improved lithium battery performance
Authors: An Qinyou , Zhang Pengfei , Wei Qiulong , He Liang , Xiong Fangyu , Sheng Jinzhi , Wang Qinqin , Mai Liqiang
Published: December 2013

Three-dimensional porous V2O5 quasi-hexagonal hierarchical microplates with tunable porosity have been fabricated by a one-step top-down strategy.
The inhibition of functional expression of calcium channels by prion protein demonstrates competition with α2δ for GPI-anchoring pathways
Authors: Alvarez-Laviada Anita , Kadurin Ivan , Senatore Assunta , Chiesa Roberto , Dolphin Annette C.
Published: December 2013

It has been shown recently that PrP (prion protein) and the calcium channel auxiliary α2δ subunits interact in neurons and expression systems [Senatore, Colleoni, Verderio, Restelli, Morini, Condliffe, Bertani, Mantovani, Canovi, Micotti, Forloni, Dolphin, Matteoli, Gobbi and Chiesa (2012) Neuron 74, 300–313]. In the present study we examined whether there was an effect of PrP on calcium currents. We have shown that when PrP is co-expressed with calcium channels formed from CaV2.1/β and α2δ-1 or α2δ-2, there is a consistent decrease in calcium current density. This reduction was absent when a PrP construct was used lacking its GPI (glycosylphosphatidylinositol) anchor. We have reported previously that α2δ subunits are able to form GPI-anchored proteins [Davies, Kadurin, Alvarez-Laviada, Douglas, Nieto-Rostro, Bauer, Pratt and Dolphin (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 1654–1659] and show further evidence in the present paper. We have characterized recently a C-terminally truncated α2δ-1 construct, α2δ-1ΔC, and found that, despite loss of its membrane anchor, it still shows a partial ability to increase calcium currents [Kadurin, Alvarez-Laviada, Ng, Walker-Gray, D’Arco, Fadel, Pratt and Dolphin (2012) J. Biol. Chem. 1287, 33554–33566]. We now find that PrP does not inhibit CaV2.1/β currents formed with α2δ-1ΔC, rather than α2δ-1. It is possible that PrP and α2δ-1 compete for GPI-anchor intermediates or trafficking pathways, or that interaction between PrP and α2δ-1 requires association in cholesterol-rich membrane microdomains. Our additional finding that CaV2.1/β1b/α2δ-1 currents were inhibited by GPI–GFP, but not cytosolic GFP, indicates that competition for limited GPI-anchor intermediates or trafficking pathways may be involved in PrP suppression of α2δ subunit function.
Linewidth of the harmonics in a microwave frequency comb generated by focusing a mode-locked ultrafast laser on a tunneling junction
Authors: Hagmann Mark J. , Stenger Frank S. , Yarotski Dmitry A.
Published: December 2013

Previous analyses suggest that microwave frequency combs (MFCs) with harmonics having extremely narrow linewidths could be produced by photodetection with a mode-locked ultrafast laser. In the MFC generated by focusing a passively mode-locked ultrafast laser on a tunneling junction, 200 harmonics from 74.254 MHz to 14.85 GHz have reproducible measured linewidths approximating the 1 Hz resolution bandwidth (RBW) of the spectrum analyzer. However, in new measurements at a RBW of 0.1 Hz, the linewidths are distributed from 0.12 to 1.17 Hz. Measurements and analysis suggest that, because the laser is not stabilized, the stochastic drift in the pulse repetition rate is the cause for the distribution in measured linewidths. It appears that there are three cases in which the RBW is (1) greater than, (2) less than, or (3) comparable with the intrinsic linewidth. The measured spectra in the third class are stochastic and may show two or more peaks at a single harmonic.
The role of the droplet deformations in the bouncing droplet dynamics
Authors: Terwagne D. , Ludewig F. , Vandewalle N. , Dorbolo S.
Published: December 2013

Droplets bouncing on a vibrated liquid bath open ways to methods of manipulating droplets, creating double emulsion, and performing pilot wave model experiments. In this work, we focus on the role of the droplet deformations in the vertical bouncing dynamics by neglecting the deformation of the surface of the bath. To be under this favorable condition, low viscous oil droplets are dropped over a highly viscous oil bath that is vibrated. These droplets bounce vertically on the surface of the bath and exhibit many periodic trajectories and resonant modes when tuning the forcing parameters, i.e., the oscillation of the bath. This complex dynamics emphasizes the interplay between elastic energy storage and energy dissipation in droplets at each bounce. We propose to model droplets using a bouncing mass-spring-damper system that mimics a deformable droplet bouncing on a non-deformable liquid bath. From the experimental measurements, we constructed bifurcation diagrams of the bouncing trajectories and challenged our bouncing spring model. The agreement between experiment and the spring model reveals that this model can be used to rationalize and predict a variety of bouncing droplets behaviors involving multi-periodicities.
Structure factor of model bidisperse ferrofluids with relatively weak interparticle interactions
Authors: Novak Ekaterina , Minina Elena , Pyanzina Elena , Kantorovich Sofia , Ivanov Alexey
Published: December 2013

In the present manuscript we develop a theoretical approach to describe the pair correlation function of bidisperse magnetic dipolar hard- and soft-spheres. We choose bidisperse system as the first step to allow for polydispersity when studying thermodynamics of magnetic fluids. Using diagram technique we calculate the virial expansion of the pair correlation function up to the first order in density and fourth order in the dipolar strength. Even though, the radial distribution functions are extremely sensitive to the steric potential, we show that the behaviour of the isotropic centre-centre structure factor is almost indifferent to the type of the short-range repulsion. We extensively compare our theoretical results to the data of molecular dynamics simulations, which helps us to understand the range of validity of the virial expansion both on density and magnetic dipolar strength. We also investigate the influence of the granulometric composition on the height, width, and position of the structure factor first peak in order to clarify whether it is possible to extract structural information from experimentally measured small angle neutron scattering intensities.
Sandwiched Rényi divergence satisfies data processing inequality
Authors: Beigi Salman
Published: December 2013

Sandwiched (quantum) α-Rényi divergence has been recently defined in the independent works of Wilde et al. [“Strong converse for the classical capacity of entanglement-breaking channels,” preprint arXiv:1306.1586 (2013)] and Müller-Lennert et al. [“On quantum Rényi entropies: a new definition, some properties and several conjectures,” preprint arXiv:1306.3142v1 (2013)]. This new quantum divergence has already found applications in quantum information theory. Here we further investigate properties of this new quantum divergence. In particular, we show that sandwiched α-Rényi divergence satisfies the data processing inequality for all values of α > 1. Moreover we prove that α-Holevo information, a variant of Holevo information defined in terms of sandwiched α-Rényi divergence, is super-additive. Our results are based on Hölder's inequality, the Riesz-Thorin theorem and ideas from the theory of complex interpolation. We also employ Sion's minimax theorem.
Time-dependence of the alpha to epsilon phase transformation in iron
Authors: Smith R. F. , Eggert J. H. , Swift D. C. , Wang J. , Duffy T. S. , Braun D. G. , Rudd R. E. , Reisman D. B. , Davis J.-P. , Knudson M. D. , Collins G. W.
Published: December 2013

Iron was ramp-compressed over timescales of 3 ≤ t(ns) ≤ 300 to study the time-dependence of the α→ε (bcc→hcp) phase transformation. Onset stresses (σα→ε)  for the transformation ∼14.8-38.4 GPa were determined through laser and magnetic ramp-compression techniques where the transition strain-rate was varied between 106 ≤μ̇α→ε(s−1) ≤ 5×108. We find σα→ε= 10.8 + 0.55 ln(μ̇α→ε) for μ̇α→ε < 106/s and σα→ε= 1.15(μ̇α→ε)0.18 for μ̇α→ε > 106/s. This μ̇ response is quite similar to recent results on incipient plasticity in Fe [Smith et al., J. Appl. Phys. 110, 123515 (2011)] suggesting that under high rate ramp compression the α→ε phase transition and plastic deformation occur through similar mechanisms, e.g., the rate limiting step for μ̇ > 106/s is due to phonon scattering from defects moving to relieve strain. We show that over-pressurization of equilibrium phase boundaries is a common feature exhibited under high strain-rate compression of many materials encompassing many orders of magnitude of strain-rate.
Enantioselectivity of (321) chiral noble metal surfaces: A density functional theory study of lactate adsorption
Authors: Franke J.-H. , Kosov D. S.
Published: December 2013

The adsorption of the chiral molecule lactate on the intrinsically chiral noble metal surfaces Pt(321), Au(321), and Ag(321) is studied by density functional theory calculations. We use the oPBE-vdW functional which includes van der Waals forces on an ab initio level. It is shown that the molecule binds via its carboxyl and the hydroxyl oxygen atoms to the surface. The binding energy is larger on Pt(321) and Ag(321) than on Au(321). An analysis of the contributions to the binding energy of the different molecular functional groups reveals that the deprotonated carboxyl group contributes most to the binding energy, with a much smaller contribution of the hydroxyl group. The Pt(321) surface shows considerable enantioselectivity of 0.06 eV. On Au(321) and Ag(321) it is much smaller if not vanishing. The chiral selectivity of the Pt(321) surface can be explained by two factors. First, it derives from the difference in van der Waals attraction of L- and D-lactate to the surface that we trace to differences in the binding energy of the methyl group. Second, the multi-point binding pattern for lactate on the Pt(321) surface is sterically more sensitive to surface chirality and also leads to large binding energy contributions of the hydroxyl group. We also calculate the charge transfer to the molecule and the work function to gauge changes in electronic structure of the adsorbed molecule. The work function is lowered by 0.8 eV on Pt(321) with much smaller changes on Au(321) and Ag(321).
The entropy of the rotational conformations of (poly)isoprene molecules and its relationship to rubber elasticity and temperature increase for moderate tensile or compressive strains
Authors: Hanson David E. , Barber John L. , Subramanian Gopinath
Published: December 2013

Molecular networks comprised of crosslinked cis-1,4 polyisoprene, often referred to as “natural rubber,” are one of the most common systems for the study of rubber elasticity. Under moderate tensile or compressive strain, network chains begin to assume straighter paths, as local molecular kinks are removed. Isoprene units along the chain backbone are mechanically forced from their equilibrium distributions of 18 possible rotational states into a smaller subset of states, restricted to more linear conformations with the greatest end-to-end distances. There are two consequences to this change: both the configurational entropy and average internal energy decrease. We find that the change in entropy, and resulting change in free energy, gives rise to an elastic force. We derive an expression for a chain extension force constant that we have incorporated in an explicit, three-dimensional meso-scale network simulation code. Using this force model, our simulations predict a macroscopic stress-strain relationship that closely matches published experimental values. We also predict a slight increase in temperature resulting from the change in average internal energy in the affected isoprene units that is consistent with experiments.
Suppression of purely elastic instabilities in the torsional flow of viscoelastic fluid past a soft solid
Authors: Neelamegam R. , Shankar V. , Das Debopam
Published: December 2013

Experiments are performed to explore the role of a soft, deformable solid layer on the purely elastic instability in the torsional flow of polymer solutions between two circular discs. The gel layer is placed on the stationary bottom plate of a rheometer, and the polymer solution is placed between the gel and the rotating top disc. The observed variation of viscosity with shear rate (or shear stress) is correlated with the presence or absence of purely elastic instability in the viscometric flow. Earlier work has shown that with increase in shear rate, the torsional flow of a polymer solution between rigid discs undergoes transition from the simple viscometric flow state to elastic turbulence via a sequence of instability modes. We combine rheological observations and flow visualization to show that the deformable solid has a profound effect on the stability of the torsional flow. In marked contrast to flow between rigid plates (where the fluid shows apparent shear-thickening at the onset of instability), the apparent viscosity continues to decrease up to a much larger value of shear rate with the presence of a soft gel. At a fixed shear rate, for flow past a soft gel, the measured stress does not exhibit marked temporal fluctuations that would otherwise be present without the soft gel. Using flow visualization, we show that secondary flow patterns that form after the instability for a rigid surface disappear for flow on soft gel surfaces. In the case of rigid surfaces, the instability is sub-critical and exhibits hysteresis behavior, which again is absent when the flow occurs past a soft solid layer. Our results show that the role of the soft deformable solid is to suppress the purely elastic instability in torsional flows of polymeric liquids for intermediate shear rates. While it is known that soft deformable solids destabilize the flow of Newtonian liquids in the absence of inertial effects, our study shows that the effect of deformability can be opposite in the torsional flow of viscoelastic liquids.
High-resolution neutron diffraction study of CuNCN: New evidence of structure anomalies at low temperature
Authors: Jacobs Philipp , Houben Andreas , Tchougréeff Andrei L. , Dronskowski Richard
Published: December 2013

Copper carbodiimide (CuNCN) is the nitrogen-containing analogue of cupric oxide. Based on high-resolution neutron-diffraction data, CuNCN's lattice parameters are derived as a function of the temperature. In accordance with a recent synchrotron study, a clear trend in the cell parameter a is observed accompanying the changing magnetic behavior. With decreasing temperature, a slowly decreases to a minimum at ∼100 K after which it rises again. The same trend—albeit more pronounced—is observed for the c lattice parameter at ∼35 K. The herein presented neutron powder-diffraction data also support the conjectured sequence of transitions from the high-temperature one-dimensional resonating valence-bond (RVB) state to a transient two-dimensional RVB state and eventually, at lowest temperatures, into another two-dimensional RVB state, presumably the ground state.
Solutions to position-dependent mass quantum mechanics for a new class of hyperbolic potentials
Authors: Christiansen H. R. , Cunha M. S.
Published: December 2013

We analytically solve the position-dependent mass (PDM) 1D Schrödinger equation for a new class of hyperbolic potentials $V_q^p(x) = -V_0\frac{\sinh ^px}{\cosh ^qx}, \, p= -2, 0, \dots q\,$Vqp(x)=−V0sinhpxcoshqx,p=−2,0,⋯q [see C. A. Downing, J. Math. Phys. 54, 072101 (2013)] among several hyperbolic single- and double-wells. For a solitonic mass distribution, \documentclass[12pt]{minimal}\begin{document}$m(x)=m_0\,\operatorname{sech}^2(x)$\end{document}m(x)=m0sech2(x), we obtain exact analytic solutions to the resulting differential equations. For several members of the class, the quantum mechanical problems map into confluent Heun differential equations. The PDM Poschl-Teller potential is considered and exactly solved as a particular case.
Time-dependent density functional theory quantum transport simulation in non-orthogonal basis
Authors: Kwok Yan Ho , Xie Hang , Yam Chi Yung , Zheng Xiao , Chen Guan Hua
Published: December 2013

Basing on the earlier works on the hierarchical equations of motion for quantum transport, we present in this paper a first principles scheme for time-dependent quantum transport by combining time-dependent density functional theory (TDDFT) and Keldysh's non-equilibrium Green's function formalism. This scheme is beyond the wide band limit approximation and is directly applicable to the case of non-orthogonal basis without the need of basis transformation. The overlap between the basis in the lead and the device region is treated properly by including it in the self-energy and it can be shown that this approach is equivalent to a lead-device orthogonalization. This scheme has been implemented at both TDDFT and density functional tight-binding level. Simulation results are presented to demonstrate our method and comparison with wide band limit approximation is made. Finally, the sparsity of the matrices and computational complexity of this method are analyzed.
Global reaction route mapping of isomerization pathways of exotic C6H molecular species
Authors: Vikas  , Kaur Gurpreet
Published: December 2013

C6H radical is known to exist in the astrophysical environment in linear form; however, it may originate from nonlinear isomeric forms. Potential energy surface of C6H is explored to search isomers of C6H and transition states connecting them. This work reports first-ever identification of reaction pathways for isomerization of C6H. The reaction route search is performed through global reaction route mapping method, which utilizes an uphill walking technique based on an anharmonic downward distortion following approach to search intermediates and transition states. The computations performed at the CASSCF/aug-cc-pVTZ, CCSD(T)/6-311++G(d,p)//DFT/B3LYP/6-311++G(d,p), and DFT/B3LYP/aug-cc-pVTZ levels of the theory identified 14 isomers (including 8 new isomeric forms of C6H) and 28 transition states. Most of the identified isomers are found to have significant multireference character. The kinetic stability and natural bond orbital analysis of the identified isomers is also investigated. The isomeric forms are further characterized using spectral analysis involving rotational constants, vibrational frequencies, and Raman scattering activities as well as analyzing the effect of isotopic substitution of hydrogen on the spectral features. This study proposes that the linear-C6H can readily isomerize to a six-member ring isomer.
Criteria for the accuracy of small polaron quantum master equation in simulating excitation energy transfer dynamics
Authors: Chang Hung-Tzu , Zhang Pan-Pan , Cheng Yuan-Chung
Published: December 2013

The small polaron quantum master equation (SPQME) proposed by Jang et al. [J. Chem. Phys. 129, 101104 (2008)] is a promising approach to describe coherent excitation energy transfer dynamics in complex molecular systems. To determine the applicable regime of the SPQME approach, we perform a comprehensive investigation of its accuracy by comparing its simulated population dynamics with numerically exact quasi-adiabatic path integral calculations. We demonstrate that the SPQME method yields accurate dynamics in a wide parameter range. Furthermore, our results show that the accuracy of polaron theory depends strongly upon the degree of exciton delocalization and timescale of polaron formation. Finally, we propose a simple criterion to assess the applicability of the SPQME theory that ensures the reliability of practical simulations of energy transfer dynamics with SPQME in light-harvesting systems.
Stability of two immiscible leaky-dielectric liquids subjected to a radial electric field in an annulus duct
Authors: Ding Zijing , Wong Teck Neng , Li Haiwang
Published: December 2013

In this paper, we investigated the stability of a two coaxial leaky dielectric fluid system flowing in an annulus duct. A constant pressure gradient was applied to drive the flow in the duct. A radial electric field was imposed between the outer and inner surfaces of the duct. Linear stability analysis was employed to discuss the influences of electric field on the capillary and interface wave instabilities. The former instability is caused by surface tension and the latter is caused by viscosity stratification at the interface. It was found that, depending on the electrical permittivities and conductivities of the two liquids, the electric field either stabilized or destabilized the flow system. Apart from that, it was found that an external electric field could impede the capillary and interface wave instabilities. Influences of the inner radius of the duct, viscosity ratio, thickness ratio, and Reynolds number on the stability of the system were discussed as well.
Self-propagating reactions in Al/Zr multilayers: Anomalous dependence of reaction velocity on bilayer thickness
Authors: Barron S. C. , Kelly S. T. , Kirchhoff J. , Knepper R. , Fisher K. , Livi K. J. T. , Dufresne E. M. , Fezzaa K. , Barbee T. W. , Hufnagel T. C. , Weihs T. P.
Published: December 2013

High temperature, self-propagating reactions are observed in vapor-deposited Al/Zr multilayered foils of overall atomic ratios 3 Al:1 Zr and 2 Al:1 Zr and nanoscale layer thicknesses; however, the reaction velocities do not exhibit the inverse dependence on bilayer thickness that is expected based on changes in the average diffusion distance. Instead, for bilayer thicknesses of 20-30 nm, the velocity is essentially constant at ∼7.7 m/s. We explore several possible explanations for this anomalous behavior, including microstructural factors, changes in the phase evolution, and phase transformations in the reactant layers, but find no conclusive explanations. We determine that the phase evolution during self-propagating reactions in foils with a 3 Al:1 Zr stoichiometry is a rapid transformation from Al/Zr multilayers to the equilibrium intermetallic Al3Zr compound with no intermediate crystalline phases. This phase evolution is the same for foils of 90 nm bilayer thicknesses and foils of bilayer thicknesses in the range of 27 nm to 35 nm. Further, for foils with a bilayer thickness of 90 nm and a 3 Al:1 Zr overall chemistry, the propagation front is planar and steady, in contrast to unsteady reaction fronts in foils with 1 Al:1 Zr overall chemistry and similar bilayer thicknesses.
The coherent interlayer resistance of a single, rotated interface between two stacks of AB graphite
Authors: Habib K. M. Masum , Sylvia Somaia S. , Ge Supeng , Neupane Mahesh , Lake Roger K.
Published: December 2013

The coherent, interlayer resistance of a misoriented, rotated interface between two stacks of AB graphite is determined for a variety of misorientation angles. The quantum-resistance of the ideal AB stack is on the order of 1 to 10 mΩ μm2. For small rotation angles, the coherent interlayer resistance exponentially approaches the ideal quantum resistance at energies away from the charge neutrality point. Over a range of intermediate angles, the resistance increases exponentially with cell size for minimum size unit cells. Larger cell sizes, of similar angles, may not follow this trend. The energy dependence of the interlayer transmission is described.
Tunable magneto-conductance and magneto-electroluminescence in polymer light-emitting electrochemical planar devices
Authors: Geng R. , Mayhew N. T. , Nguyen T. D.
Published: December 2013

We report studies of magneto-conductance (MC) and magneto-electroluminescence (MEL) in polymer light-emitting electrochemical planar devices using “super-yellow” poly-(phenylene vinylene). We observed consistent negative MC while MEL becomes positive when electroluminescence quantum efficiency (ELQE) increases. At an optimal ELQE, the MC has a much narrower width than the MEL, indicating that the MC and MEL do not share a common origin. However, MC reverses and has the same width as MEL when exposed to a threshold laser power. We show that the e-h pair model can explain the positive MEL and MC while the negative MC can be explained by the bipolaron model.
Eight-band k·p modeling of InAs/InGaAsSb type-II W-design quantum well structures for interband cascade lasers emitting in a broad range of mid infrared
Authors: Ryczko K. , Sęk G. , Misiewicz J.
Published: December 2013

Band structure properties of the type-II W-design AlSb/InAs/GaIn(As)Sb/InAs/AlSb quantum wells have been investigated theoretically in a systematic manner and with respect to their use in the active region of interband cascade laser for a broad range of emission in mid infrared between below 3 to beyond 10 μm. Eight-band k·p approach has been utilized to calculate the electronic subbands. The fundamental optical transition energy and the corresponding oscillator strength have been determined in function of the thickness of InAs and GaIn(As)Sb layers and the composition of the latter. There have been considered active structures on two types of relevant substrates, GaSb and InAs, introducing slightly modified strain conditions. Additionally, the effect of external electric field has been taken into account to simulate the conditions occurring in the operational devices. The results show that introducing arsenic as fourth element into the valence band well of the type-II W-design system, and then altering its composition, can efficiently enhance the transition oscillator strength and allow additionally increasing the emission wavelength, which makes this solution prospective for improved performance and long wavelength interband cascade lasers.
Spin-polarized hydrogen adsorbed on the surface of superfluid 4He
Authors: Marín J. M. , Markić L. Vranješ , Boronat J.
Published: December 2013

The experimental realization of a thin layer of spin-polarized hydrogen H↓ adsorbed on top of the surface of superfluid 4He provides one of the best examples of a stable, nearly two-dimensional (2D) quantum Bose gas. We report a theoretical study of this system using quantum Monte Carlo methods in the limit of zero temperature. Using the full Hamiltonian of the system, composed of a superfluid 4He slab and the adsorbed H↓ layer, we calculate the main properties of its ground state using accurate models for the pair interatomic potentials. Comparing the results for the layer with the ones obtained for a strictly 2D setup, we analyze the departure from the 2D character when the density increases. Only when the coverage is rather small the use of a purely 2D model is justified. The condensate fraction of the layer is significantly larger than in 2D at the same surface density, being as large as 60% at the largest coverage studied.
Revisiting dynamics near a liquid-liquid phase transition in Si and Ga: The fragile-to-strong transition
Authors: Cajahuaringa Samuel , de Koning Maurice , Antonelli Alex
Published: December 2013

Using molecular dynamics simulations we analyze the dynamics of two atomic liquids that display a liquid-liquid phase transition (LLPT): Si described by the Stillinger-Weber potential and Ga as modeled by the modified embedded-atom model. In particular, our objective is to investigate the extent to which the presence of a dip in the self-intermediate scattering function is a manifestation of an excess of vibrational states at low frequencies and may be associated with a fragile-to-strong transition (FTST) across the LLPT, as suggested recently. Our results suggest a somewhat different picture. First, in the case of Ga we observe the appearance of an excess of vibrational states at low frequencies, even in the absence of the appearance of a dip in the self-intermediate scattering function across the LLPT. Second, studying the behavior of the shear viscosities traversing the LLPTs we find that both substances are fragile in character above and below their respective LLPT temperatures. Instead of a FTST in an absolute sense these findings are more in line with a view in which the LLPTs are accompanied by a transition from a more fragile to a less fragile liquid. Furthermore, we do not find this transition to correlate with the presence of a dip in the intermediate scattering function.
Nonlinear electrostatic excitations in magnetized dense plasmas with nonrelativistic and ultra-relativistic degenerate electrons
Authors: Mahmood S. , Sadiq Safeer , Haque Q.
Published: December 2013

Linear and nonlinear electrostatic waves in magnetized dense electron-ion plasmas are studied with nonrelativistic and ultra-relativistic degenerate and singly, doubly charged helium (He+, He++) and hydrogen (H+) ions, respectively. The dispersion relation of electrostatic waves in magnetized dense plasmas is obtained under both the energy limits of degenerate electrons. Using reductive perturbation method, the Zakharov-Kuznetsov equation for nonlinear propagation of electrostatic solitons in magnetized dense plasmas is derived for both nonrelativistic and ultra-relativistic degenerate electrons. It is found that variations in plasma density, magnetic field intensity, different mass, and charge number of ions play significant role in the formation of electrostatic solitons in magnetized dense plasmas. The numerical plots are also presented for illustration using the parameters of dense astrophysical plasma situations such as white dwarfs and neutron stars exist in the literature. The present investigation is important for understanding the electrostatic waves propagation in the outer periphery of compact stars which mostly consists of hydrogen and helium ions with degenerate electrons in dense magnetized plasmas.
A fluctuational electrodynamics model for the optimization of light-extraction efficiency in thin-film light-emitting diodes
Authors: Heikkilä Oskari , Oksanen Jani , Tulkki Jukka
Published: December 2013

The rapid development of thin film light-emitting diodes (LEDs) has enabled the enhancement of the light extraction beyond geometrical limits but more quantitative understanding of the underlying optical processes is required to fully optimize the extraction. We present first-principle calculations of the light extraction efficiency and optical energy flow in thin-film LEDs. The presented model generalizes the methods of fluctuational electrodynamics to excited semiconductors and simultaneously accounts for wave optical effects, e.g., interference and near-field coupling as well as the internal absorption of the light-emitting material in determining the rate of light emission and internal dissipation in the optical cavity formed by a planar LED. The calculations show that in structures with a metallic mirror, the emissivity of the active region can approach unity at selected wavelengths, even when the nominal emissivity of the active region is only moderate. However, the results also show that near-field coupling of emission from the active region to the mirror can provide a substantial non-radiative loss channel reducing the maximum light extraction efficiency to 0.67 in our example setup. These losses can be partly compensated by the efficient photon recycling enabled by thick active regions that quench emission to confined modes and thereby reduce parasitic absorption.
Relation between delayed feedback and delay-coupled systems and its application to chaotic lasers
Authors: Soriano Miguel C. , Flunkert Valentin , Fischer Ingo
Published: December 2013

We present a systematic approach to identify the similarities and differences between a chaotic system with delayed feedback and two mutually delay-coupled systems. We consider the general case in which the coupled systems are either unsynchronized or in a generally synchronized state, in contrast to the mostly studied case of identical synchronization. We construct a new time-series for each of the two coupling schemes, respectively, and present analytic evidence and numerical confirmation that these two constructed time-series are statistically equivalent. From the construction, it then follows that the distribution of time-series segments that are small compared to the overall delay in the system is independent of the value of the delay and of the coupling scheme. By focusing on numerical simulations of delay-coupled chaotic lasers, we present a practical example of our findings.