bluuebunny/crossref_metadata_2025 huggingface dataset:
Lie Group Analysis for a Mixed Convective Flow and Heat Mass Transfer Over a Permeable Stretching Surface with Soret and Dufour Effects
Authors: Abdel-Rahman Reda G. , Megahed Ahmed M.
Published: November 2013

The Lie group transformation method is applied for solving the problem of mixed convection flow with mass transfer over a permeable stretching surface with Soret and Dufour effects. The application of Lie group method reduces the number of independent variables by one and consequently the system of governing partial differential equations reduces to a system of ordinary differential equations with appropriate boundary conditions. Further, the reduced non-linear ordinary differential equations are solved numerically by using the shooting method. The effects of various parameters governing the flow and heat transfer are shown through graphs and discussed. Our aim is to detect new similarity variables which transform our system of partial differential equations to a system of ordinary differential equations. In this work a special attention is given to investigate the effect of the Soret and Dufour numbers on the velocity, temperature and concentration fields above the sheet.
Comparisons of Flow and Mixing Characteristics between Unforced and Excited Elevated Transverse Jets
Authors: Hsu C. M. , Huang R. F.
Published: November 2013

The influences of acoustic excitation on the velocity field and mixing characteristic of a jet in cross-flow were investigated in a wind tunnel. The acoustic excitation waves at resonance Strouhal number were generated by a loudspeaker. The time-averaged velocity field and streamlines of the excited elevated transverse jet in the symmetry plane were measured by a high-speed particle image velocimetry. The visual penetration height and spread width were obtained by using an image processing technique. The dispersion characteristics were obtained from the tracer-gas concentration measurement. The results showed that the streamline pattern of the non-excited transverse jet was significantly modified by the acoustic excitation—the bent streamlines evolved from the jet exit escalated and the vortex rings in the jet and tube wakes and the recirculation bubble in the jet wake disappeared. The time-averaged velocity distributions revealed that the excited transverse jet produces large momentum in the up-shooting direction so that the velocity trajectories were located at levels higher than those of the non-excited one. The mixing characteristics, which include the visual penetration height, spread width, and dispersion, were drastically improved by the acoustic excitation due to the changes in the flow structures. The excited transverse jet characterized at larger jet-to-crossflow momentum flux ratios presented larger improvement in the mixing characteristics than at lower jet-to-crossflow momentum flux ratios.
Word order, referential expression, and case cues to the acquisition of transitive sentences in Italian
Authors: ABBOT-SMITH KIRSTEN , SERRATRICE LUDOVICA
Published: November 2013

In Study 1 we analyzed Italian child-directed-speech (CDS) and selected the three most frequent active transitive sentence frames used with overt subjects. In Study 2 we experimentally investigated how Italian-speaking children aged 2;6, 3;6, and 4;6 comprehended these orders with novel verbs when the cues of animacy, gender, and subject–verb agreement were neutralized. For each trial, children chose between two videos (e.g., horse acting on cat versus cat acting on horse), both involving the same action. The children aged 2;6 comprehended S + object-pronoun + V (soprov) significantly better than S + V + object-noun (svonoun). We explain this in terms of cue collaboration between a low cost cue (case) and the firstargument = agent cue which we found to be reliable 76% of the time. The most difficult word order for all age groups was the object-pronoun + V + S (oprovs). We ascribe this difficulty to cue conflict between the two most frequent transitive frames found in CDS, namely V + object-noun and object-pronoun + V.
Talking theory of mind talk: young school-aged children's everyday conversation and understanding of mind and emotion
Authors: DE ROSNAY MARC , FINK ELIAN , BEGEER SANDER , SLAUGHTER VIRGINIA , PETERSON CANDIDA
Published: November 2013

Links between young children's everyday use of mindful conversational skills and their success on laboratory tests of theory of mind understanding (ToM) were evaluated. Using published scales, teachers rated the conversational behavior and shyness of 129 children aged 60 to 101 months (M = 78·8 months) who were in their first years of primary school. The children also took batteries of first- and second-order false-belief tests along with tests of emotion understanding and general language ability. Correlational and regression analyses showed that performance on false-belief tests of ToM significantly predicted children's competence at reading others' minds in their everyday conversational interactions. Furthermore, these links transcended individual differences in language ability, shy personality, emotion understanding, and age. These findings augment and extend a growing body of evidence linking performance on laboratory ToM tests to socially competent real-world behavior.
Production and perception of listener-oriented clear speech in child language
Authors: SYRETT KRISTEN , KAWAHARA SHIGETO
Published: November 2013

In this paper, we ask whether children are sensitive to the needs of their interlocutor, and, if so, whether they – like adults – modify acoustic characteristics of their speech as part of a communicative goal. In a production task, preschoolers participated in a word learning task that favored the use of clear speech. Children produced vowels that were longer, more intense, more dispersed in the vowel space, and had a more expanded F0 range than normal speech. Two perception studies with adults showed that these acoustic differences were perceptible and were used to distinguish normal and clear speech styles. We conclude that preschoolers are sensitive to aspects of the speaker–hearer relationship calling upon them to modify their speech in ways that benefit their listener.
The Complexity Problem in Future Multisensor Navigation and Positioning Systems: A Modular Solution
Authors: Groves Paul D.
Published: November 2013

Navigation and positioning system users are demanding greater accuracy and reliability in ever more challenging environments. This is driving a wave of rapid innovation, with the result that multisensor integrated navigation systems will become much more complex. This introduces a number of problems, including how to find the necessary expertise to integrate a diverse range of technologies, how to combine technologies from different organisations that wish to protect their intellectual property, and how to incorporate new navigation technologies and methods without having to redesign the whole system. It also makes it desirable to share development effort over a range of different applications. To address this, the feasibility of a modular approach to the design and development of multisensor integrated navigation and positioning systems is analysed. Assessments of the requirements of different user communities and the adaptability of the different navigation and positioning technologies to different contexts and requirements are presented. Based on this, the adoption of an open interface standard for modular integration is recommended and the issues to be resolved in developing that standard are outlined.
Evidence of formation of the tridymite form of AlPO4 in some municipal sewage sludge ashes
Authors: Peplinski B. , Adam C. , Adamczyk B. , Müller R. , Schadrack R. , Michaelis M. , Emmerling F. , Reuther H. , Menzel M.
Published: November 2013

Evidence is provided that the tridymite component observed in the X-ray diffraction patterns of some sewage sludge ashes (SSAs) should not be interpreted as the tridymite modification of SiO2 but as the tridymite form of AlPO4. This proof is based on a combined X-ray Powder Diffraction (XRD), X-ray fluorescence (XRF) and Mossbauer spectroscopy investigation of two SSAs produced at two fluidized bed incineration facilities, located in different municipalities and operated differently. The structural and chemical characterization was carried out on the ‘as received’ SSA samples as well as on the residues of these two SSAs pretreated by leaching in citric acid. In addition, direct proof is presented that the tridymite form of AlPO4 does crystallize from X-ray amorphous precursors under conditions that mimic the huge heating rate and short retention time (just seconds at T ≈ 850 °C) typical for fluidized bed incinerators.
Synchrotron X-ray powder diffraction study on synthetic Sr-Fresnoite
Authors: Bell A.M.T. , Liermann H-P. , Bednarcik J. , Henderson C.M.B.
Published: November 2013

The Sr analogue of the mineral fresnoite (Sr2TiSi2O8) is of interest as a potential storage medium for radioactive Sr from nuclear waste. No high or low temperature crystal structure information is known on this phase. Therefore high-resolution synchrotron X-ray powder diffraction measurements have been done on a synthetic sample of Sr-fresnoite in the temperature range 87-1223K. This was done as a test experiment using the HRPD beamline P02.1 at PETRA-III, DESY. Synchrotron X-ray wavelengths of 0.2067(3)Å (293K and 573-1223K) and 0.2079(3)Å (87-499K) were used. Powder diffraction data were collected with a counting time of 30s using a PerkinElmer XRD 1621 flat panel image plate detector. CeO2was included as an internal standard to calibrate the sample to detector distance. TheP4bmtetragonal crystal structure of fresnoite (Ba2TiSi2O8) was used as a starting model for Sr-fresnoite. Small amounts of SrTiO3and SrSiO3were also found as impurities in this sample; therefore four-phase Rietveld refinements were done. TheP4bmfresnoite structure is retained over the temperature range 87-1223K.
Lattice deformation measurements via “on site X-ray diffraction”
Authors: Berti G. , de Marco F. , del Seppia M. E.
Published: November 2013

The present paper is about the estimation of lattice deformation from data collected from manufactures directly on site. The aim here is to give evidence that the concept of the Mean Equivalent Lattice (MEL), when applied to “on site X-Ray Diffraction” is the basis for a reliable qualification of the material rheology to external solicitations. Such method allows for the identification of lattice deformations without resorting to the computation of the residual stress with using the elasticity constants (i.e. tensile, shear and rigidity constants E, μ, ν); these elasticity constants descend from the classical theory of solid mechanics, where the continuum mechanics and the material isotropic model are the fundaments. Any MEL deformation is instead related to the variation of the d-spacing among lattice planes which are connected to the anisotropic atomic arrangement. So the macroscopic scale is constituted by a number of MELs and related boundaries. The recent on site X-ray diffraction technology may offer effective and easy solutions, with a significant impact on reliability of results, simplification, economy and time consuming.
Enclosing the functional properties of pyrazolato-based coordination polymers within a structural frame: the role of laboratory X-ray powder diffraction
Authors: Galli Simona , Masciocchi Norberto
Published: November 2013

Ab initio X-ray powder diffraction structural analyses from laboratory data have been widely employed in the characterization of coordination polymers not affording single crystals of suitable quality to undergo conventional structural determinations. This is particularly true for coordination polymers built upon strong ligand-to-metal bonds, as those formed by anionic, nitrogen-based heterocycles - pyrazolates, imidazolates, pyrimidinolates and more complex moieties derived therefrom. More than one hundred species belonging to this class have been structurally characterized in the last three decades, affording key, otherwise inaccessible stereochemical and supramolecolar features. This contribution summarizes our most recent experience in the XRPD structural characterization of pyrazolato-based coordination polymers, devoting a special consideration to the methodologies and tricks which allowed us to juxtapose the structural description of these materials to their physico-chemical and, above all, functional properties.
Domain structure investigation of non-stoichiometric strontium ferrites and cobaltites
Authors: Ancharova U.V. , Cherepanova S.V.
Published: November 2013

Monte Carlo domain structure simulation and Debye equation calculation of XRD patterns were used to confirm the formation of domain structure and investigate its peculiarities. Correspondence of simulated XRD patterns with synchrotron powder diffraction experiments is achieved on the conditions that beside of 90o rotations of brownmillerite-like domains inside perovskite-like matrix each domain contains areas with perpendicularly oriented tetrahedral chains. Influence of such parameters as stoichiometry, average domain size, orthorhombic distortion degree on the XRD patterns is considered.
Crystalline domain size and faulting in the new NIST SRM 1979 zinc oxide
Authors: Cline J. P. , Leoni M. , Black D. , Henins A. , Bonevich J. E. , Whitfield P. S. , Scardi P.
Published: November 2013

A NIST SRM certified to address the issue of crystallite size measurement through a line profile analysis has been under development for several years. In order to prepare the feedstock for the SRM, nano-crystalline zinc oxide was produced from thermal decomposition of zinc oxalate. The thermal processing parameters were chosen to yield particles in two size ranges, one with a distribution centered at approximately 15 nm and another centered at 60 nm. Certification data were collected on a NIST-built diffractometer equipped with a Johansson incident beam monochromator and scintillation detector. Data were analyzed using whole powder pattern modeling to determine microstructural data. The analysis shows domains to be in the form of discs of a fairly small aspect ratio. While both materials exhibit the effects of stacking faults through broadening of specific hkl reflections, their presence in the 60 nm is more difficult to discern. Images of the crystallites obtained with transmission electron microscopy are consistent with the results from the X-ray diffraction analyses.
A review of Debye Function Analysis
Authors: Beyerlein Kenneth R.
Published: November 2013

The employment of the Debye function to model line profiles in the powder diffraction pattern from small crystallites is briefly reviewed. It is also demonstrated that for the case of very small spherical particles, it is necessary to average patterns from multiple constructions of the particle to have complete agreement with reciprocal space models. In doing so it is demonstrated that the technique of Debye function analysis is best suited for systems with only a few possible atomic arrangements.
Finding Hidden Cliques in Linear Time with High Probability
Authors: DEKEL YAEL , GUREL-GUREVICH ORI , PERES YUVAL
Published: November 2013

We are given a graphGwithnvertices, where a random subset ofkvertices has been made into a clique, and the remaining edges are chosen independently with probability$\frac12$. This random graph model is denoted$G(n,\frac12,k)$. The hidden clique problem is to design an algorithm that finds thek-clique in polynomial time with high probability. An algorithm due to Alon, Krivelevich and Sudakov [3] uses spectral techniques to find the hidden clique with high probability when$k = c \sqrt{n}$for a sufficiently large constantc> 0. Recently, an algorithm that solves the same problem was proposed by Feige and Ron [12]. It has the advantages of being simpler and more intuitive, and of an improved running time ofO(n2). However, the analysis in [12] gives a success probability of only 2/3. In this paper we present a new algorithm for finding hidden cliques that both runs in timeO(n2) (that is, linear in the size of the input) and has a failure probability that tends to 0 asntends to ∞. We develop this algorithm in the more general setting where the clique is replaced by a dense random graph.
AFLP and PBA polymorphisms in an endangered medicinal plant,Rhazya stricta, in Pakistan
Authors: Gilani Syed Abdullah , Hirano Ryoko , Fujii Yoshiharu , Watanabe Kazuo N.
Published: November 2013

Rhazya strictais an endangered medicinal plant that is under severe human pressure as a result of commercial harvesting. As a model of habitat fragmentation, we selected the Kohat Plateau in the Pakistani Himalaya, where populations are fragmented, with less than 100 individuals per population. We hypothesized that the populations may be threatened by rapid habitat fragmentation and by unsustainable utilization of the plant. We analysed P450-based analogue functional genomic markers and amplified fragment length polymorphism markers from six populations ofR. strictaon the Kohat Plateau, and examined their variations both within and among the populations. Both the marker groups revealed lower genetic differentiation among the populations and higher genetic differentiation within the populations as a result of high gene flow. The results confirmed that habitat fragmentation is being caused by severe human pressure, and although signs of genetic erosion are not yet visible, they seem likely to become visible in the future. Therefore, the conservation ofR. strictapopulations is necessary.
Unlimited access to low-energy diet causes acute malnutrition in dams and alters biometric and biochemical parameters in offspring
Authors: do Nascimento E. , de Santana Muniz G. , das Graças de Santana Muniz M. , de Souza Alexandre L. , da Rocha L. S. , Leandro C. G. , de Castro R. M. , Bolaños-Jimenez F.
Published: November 2013

Here we analyze the outcomes of unlimited access to a low-energy (LE) diet in dams and their offspring. At 3 weeks’ gestation, pregnant Wistar rats were divided into two groups: (1) the control group received a normoenergetic diet; and (2) the experimental group received the LE diet. In dams, lactation outcomes, food intake, body weight, plasma IGF-1, prealbumin, transferrin and retinol-binding protein levels were evaluated; in offspring, biometric and biochemical parameters and food intake were evaluated. No differences were observed during pregnancy. However, after lactation, dams that received the LE diet demonstrated significant reductions in body weight (P<0.05), plasma IGF-1 (P=0.01), prealbumin and visceral fat (P<0.001). Pups born to dams that received the LE diet demonstrated reduced body length and weight at weaning (P<0.001) and were lighter than the control animals at the end of the experimental period. Pups also demonstrated reduced plasma, low-density lipoprotein (P=0.04), triglycerides (P=0.002) and glucose levels (P<0.05), and differences were noted in visceral fat. These results indicate that feeding dams with LE diet during the reproductive period induces acute malnutrition and impairs the growth and development of offspring, as well as certain metabolic parameters.
The Effects of Mental Arithmetic Strain on Behavioral and Physiological Responses
Authors: Salvia Emilie , Guillot Aymeric , Collet Christian
Published: November 2013

Everyday activities require different levels of mental load depending on both external and internal task demands, and the resulting strain is likely to drastically influence the forthcoming performance. In this study, we aimed to determine how objective and subjective task constraints may respectively impact strain and performance. Thirty participants, recruited for their affinity or avoidance for mental arithmetic, were confronted with calculations of varying difficulty. Data showed that Reaction Times (RTs), as well as electrodermal (EDR) and heart rate (HR) response durations increased along with task difficulty and performance decrement. Good performance elicited weaker sympathetic involvement, attesting that positive emotions are likely to elicit less strain than negative emotions. The “approach” group exhibited longer electrodermal responses than the “avoidance” group, especially when performing difficult computations. The “approach” group also showed increased EDR duration along with increased RT, while the “avoidance” group exhibited decreased EDR duration along with increased RT. Therefore, individuals with mental arithmetic affinity might be more involved than those with avoidance. Finally, HR deceleration prior to mental arithmetic did not vary as a function of the independent variables, thus meaning that attention increased to the same extent regardless of the experimental condition. Thus, the resulting strain depends on task difficulty, response accuracy, and group membership, the most sensitive physiological indices being EDR duration and HR response duration.
The medaka mutation tintachina sheds light on the evolution of V-ATPase B subunits in vertebrates
Authors: Müller Claudia , Maeso Ignacio , Wittbrodt Joachim , Martínez-Morales Juan R.
Published: November 2013

Vacuolar-type H+ ATPases (V-ATPases) are multimeric protein complexes that play a universal role in the acidification of intracellular compartments in eukaryotic cells. We have isolated the recessive medaka mutation tintachina (tch), which carries an inactivating modification of the conserved glycine residue (G75R) of the proton pump subunit atp6v1Ba/vatB1. Mutant embryos show penetrant pigmentation defects, massive brain apoptosis and lethality before hatching. Strikingly, an equivalent mutation in atp6v1B1 (G78R) has been reported in a family of patients suffering from distal renal tubular acidosis (dRTA), a hereditary disease that causes metabolic acidosis due to impaired kidney function. This poses the question as to how molecularly identical mutations result in markedly different phenotypes in two vertebrate species. Our work offers an explanation for this phenomenon. We propose that, after successive rounds of whole-genome duplication, the emergence of paralogous copies allowed the divergence of the atp6v1B cis-regulatory control in different vertebrate groups.
Synthesis of 1-substituted epibatidine analogues and their in vitro and in vivo evaluation as α4β2 nicotinic acetylcholine receptor ligands
Authors: Heugebaert Thomas S. A. , Van Overtveldt Melissa , De Blieck Ann , Wuyts Benjamin , Augustijns Patrick , Ponce-Gámez Eugenia , Rivera Alicia , De Groote Dominic , Lefebvre Romain A. , Wouters Patrick , Meert Theo , Devulder Jacques , Stevens Christian V.
Published: November 2013

Five symmetric epibatidine analogues were evaluated for bioactivity, two selectively bind the α4β2 nAChR.
Intramolecular 5-endo-trig aminopalladation of β-hydroxy-γ-alkenylamine: efficient route to a pyrrolidine ring and its application for the synthesis of (−)-8,8a-di-epi-swainsonine
Authors: Singh Priyanka , Panda Gautam
Published: November 2013

The intramolecular aminopalladation reaction of l-serine derived β-hydroxy-γ-alkenylamines undergoes 5-endo-trig cyclization to furnish pyrrolidine rings in high yields. The pyrrolidine thus obtained were elaborated to the synthesis of (−)-8,8a-di-epi-swainsonine.
Purinergic stimulation of K+-dependent Na+/Ca2+ exchanger isoform 4 requires dual activation by PKC and CaMKII
Authors: Yang Xu , Lytton Jonathan
Published: November 2013

K+-dependent Na+/Ca2+-exchanger isoform 4 (NCXK4) is one of the most broadly expressed members of the NCKX (K+-dependent Na+/Ca2+-exchanger) family. Recent data indicate that NCKX4 plays a critical role in controlling normal Ca2+ signal dynamics in olfactory and other neurons. Synaptic Ca2+ dynamics are modulated by purinergic regulation, mediated by ATP released from synaptic vesicles or from neighbouring glial cells. Previous studies have focused on modulation of Ca2+ entry pathways that initiate signalling. Here we have investigated purinergic regulation of NCKX4, a powerful extrusion pathway that assists in terminating Ca2+ signals. NCKX4 activity was stimulated by ATP through activation of the P2Y receptor signalling pathway. Stimulation required dual activation of PKC (protein kinase C) and CaMKII (Ca2+/calmodulin-dependent protein kinase II). Mutating T312, a putative PKC phosphorylation site on NCKX4, partially prevented purinergic stimulation. These data illustrate how purinergic regulation can shape the dynamics of Ca2+ signalling by activating a signal damping and termination pathway.
Shear propagation in the terahertz dynamics of water-glycerol mixtures
Authors: Cunsolo Alessandro , Kodituwakku Chaminda N. , Bencivenga Filippo , Said Ayman H.
Published: November 2013

Inelastic X-ray and neutron scattering techniques were jointly used to investigate the dynamics of water-glycerol mixtures at different concentrations and temperatures. It was observed that even relatively low concentrations of glycerol increase the damping of shear modes, as a consequence of the known ability of glycerol to disrupt the hydrogen bond network of water. A similar trend was observed when increasing the temperature, which suggests the presence of a locus in the concentration-temperature plane marking a crossover in the shear modulus.
Tuning patterning conditions by co-adsorption of gases: Br2 and H2 on Si(001)
Authors: Biswas Sananda , Deshpande Sadanand V. , Dunn Derren N. , Narasimhan Shobhana
Published: November 2013

We have studied the co-adsorption of Br2 and H2 on Si(001), and obtained co-adsorption energies and the surface phase diagram as a function of the chemical potential and pressure of the two gases. To do this, we have used density functional theory calculations in combination with ab initio atomistic thermodynamics. Over large ranges of bromine and hydrogen chemical potentials, the favored configuration is found to be either one with only Br atoms adsorbed on the surface, at full coverage, in a (3 × 2) pattern, or a fully H-covered surface in a (2 × 1) structure. However, we also find regions of the phase diagram where there are configurations with either only Br atoms, or Br and H atoms, arranged in a two-atom-wide checkerboard pattern with a (4 × 2) surface unit cell. Most interestingly, we find that by co-adsorbing with H2, we bring this pattern into a region of the phase diagram corresponding to pressures that are significantly higher than those where it is observed with Br2 alone. We also find small regions of the phase diagram with several other interesting patterns.
Density functional theory study of neutral and oxidized thiophene oligomers
Authors: Dai Yafei , Wei Chengwei , Blaisten-Barojas Estela
Published: November 2013

The effect of oxidation on the energetics and structure of thiophene (Th) oligomers is studied with density functional theory at the B3PW91/6-311++G(d,p) level. Neutral n-Th oligomers (2 < n < 13) are gently curved planar chains. Ionization potential and electron affinity results show that n-Th oligomers are easier to be oxidized as their chain length increases. Oxidation states +2, +4, +6, and +8 are energetically stable in 12-Th. Upon oxidation the conjugated backbone of 12-Th switches from extended benzenoid phase to quinoid phase localized on groups of monomers regularly spaced along the chain. Oxidized states +2, +4, +6, and +8 of 12-Th display two +1e localized at the ends of their chains only because of the finite size of the chains. In 12-Th this end-effect extends over the two terminal monomers forming a positive-negative charge duet. This peculiar charge localization makes n-Th oligomers different from other conducting polymers with similar structure, such as polypyrrole. The spectrum of single-electron molecular states of oxidized 12-Th displays two localized single-electron states in the HOMO-LUMO energy gap per +2 oxidation state. Oligothiophene 12-Th doped with F atoms at 1:2 concentration presents a charge transfer of 3.4 e from oligomer to dopants that increases to 4.8 e in the presence of solvent. The charge distribution in these F-doped oligomers is similar to the +4 oxidation state of 12-Th. It is predicted that dopants produce an enhanced charge transfer localized in the proximity of their locations enhancing the formation of bipolarons in the central part of the oligomer chain.
Tapered nanofiber trapping of high-refractive-index nanoparticles
Authors: Swaim Jon D. , Knittel Joachim , Bowen Warwick P.
Published: November 2013

A nanofiber-based optical tweezer is demonstrated. Trapping is achieved by combining attractive near-field optical gradient forces with repulsive electrostatic forces. Silica-coated Fe2O3 nanospheres of 300 diameter are trapped as close as 50 nm away from the surface with 810 μW of optical power, with a maximum trap stiffness of 2.7 pN μm−1. Electrostatic trapping forces up to 0.5 pN are achieved, a factor of 50 larger than those achievable for the same optical power in conventional optical tweezers. Efficient collection of the optical field directly into the nanofiber enables ultra-sensitive tracking of nanoparticle motion and extraction of its characteristic Brownian motion spectrum, with a minimum position sensitivity of 3.4 Å/Hz.
Ion finite Larmor radius effects on the interchange instability in an open system
Authors: Katanuma I. , Sato S. , Okuyama Y. , Kato S. , Kubota R.
Published: November 2013

A particle simulation of an interchange instability was performed by taking into account the ion finite Larmor radius (FLR) effects. It is found that the interchange instability with large FLR grows in two phases, that is, linearly growing phase and the nonlinear phase subsequent to the linear phase, where the instability grows exponentially in both phases. The linear growth rates observed in the simulation agree well with the theoretical calculation. The effects of FLR are usually taken in the fluid simulation through the gyroviscosity, the effects of which are verified in the particle simulation with large FLR regime. The gyroviscous cancellation phenomenon observed in the particle simulation causes the drifts in the direction of ion diamagnetic drifts.
Double quantum dot in a quantum dash: Optical properties
Authors: Kaczmarkiewicz Piotr , Machnikowski Paweł , Kuhn Tilmann
Published: November 2013

We study the optical properties of highly elongated, highly flattened quantum dot structures, also referred to as quantum dashes, characterized by the presence of two trapping centers located along the structure. Such a system can exhibit some of the properties characteristic for double quantum dots. We show that sub- and super-radiant states can form for certain quantum dash geometries, which is manifested by a pronounced transfer of intensity between spectral lines, accompanied by the appearance of strong electron-hole correlations. We also compare exciton absorption spectra and polarization properties of a system with a single and double trapping center and show how the geometry of multiple trapping centers influences the optical properties of the system. We show that for a broad range of trapping geometries the relative absorption intensity of the ground state is larger than that of the lowest excited states, contrary to the quantum dash systems characterized by a single trapping center. Thus, optical properties of these structures are determined by fine details of their morphology.
The Rayleigh-Taylor Instability driven by an accel-decel-accel profile
Authors: Ramaprabhu P. , Karkhanis V. , Lawrie A. G. W.
Published: November 2013

We describe numerical simulations of the miscible Rayleigh-Taylor (RT) instability driven by a complex acceleration history, g(t), with initially destabilizing acceleration, g > 0, an intermediate stage of stabilizing deceleration, g < 0, and subsequent destabilizing acceleration, g > 0. Initial perturbations with both single wavenumber and a spectrum of wavenumbers (leading to a turbulent front) have been considered with these acceleration histories. We find in the single-mode case that the instability undergoes a so-called phase inversion during the first acceleration reversal from g > 0 to g < 0. If the zero-crossing of g(t) occurs once the instability growth has reached a state of nonlinear saturation, then hitherto rising bubbles and falling spikes reverse direction and collide, causing small-scale structures to emerge and enhancing molecular mixing in the interfacial region. Beyond the second stationary point of g(t) where once again g > 0, the horizontal mean density profile becomes RT-unstable and the interfacial region continues to enlarge. Secondary Kelvin-Helmholtz-unstable structures on the near-vertical sheared edges of the primary bubble have an Atwood-number-dependent influence on the primary RT growth rate. This Atwood number dependence appears to occur because secondary instabilities strongly promote mixing, but the formation of these secondary structures is suppressed at large density differences. For multi-mode initial perturbations, we have selected an initial interfacial amplitude distribution h0 (λ) that rapidly achieves a self-similar state during the initial g > 0 acceleration. The transition from g > 0 to g < 0 induces significant changes in the flow structure. As with the single-mode case, bubbles and spikes collide during phase inversion, though in this case the interfacial region is turbulent, and the region as a whole undergoes a period of enhanced structural breakdown. This is accompanied by a rapid increase in the rate of molecular mixing, and increasing isotropy within the region. During the final stage of g > 0 acceleration, self-similar RT mixing re-emerges, together with a return to anisotropy. We track several turbulent statistical quantities through this complex evolution, which we present as a resource for the validation and refinement of turbulent mix models.
An investigation into electron scattering from pyrazine at intermediate and high energies
Authors: Sanz A. G. , Fuss M. C. , Blanco F. , Gorfinkiel J. D. , Almeida D. , da Silva F. Ferreira , Limão-Vieira P. , Brunger M. J. , García G.
Published: November 2013

Total electron scattering cross sections for pyrazine in the energy range 10–500 eV have been measured with a new magnetically confined electron transmission-beam apparatus. Theoretical differential and integral elastic, as well as integral inelastic, cross sections have been calculated by means of a screening-corrected form of the independent-atom representation (IAM-SCAR) from 10 to 1000 eV incident electron energies. The present experimental and theoretical total cross sections show a good level of agreement, to within 10%, in the overlapping energy range. Consistency of these results with previous calculations (i.e., the R-matrix and Schwinger Multichannel methods) and elastic scattering measurements at lower energies, below 10 eV, is also discussed.
In situ study on layer-by-layer growth in vapor deposition of linear long-chain molecules using a quartz crystal microbalance
Authors: Kubono Atsushi , Minagawa Yuko , Ito Takaya
Published: November 2013

The thin film formation at the initial stage of the vapor deposition of organic long-chain molecules was monitored using a quartz crystal microbalance. The growth rate of the thin films was strongly dependent on the substrate temperature: at substrate temperatures below 287 K, the film growth proceeded at a uniform rate while no film was formed above 297 K owing to a higher rate of re-evaporation. Of particular interest is a stepwise increase in the amount of molecules adsorbed at 293 K, where each step height corresponded to the molecular length. These results suggest that layer-by-layer growth proceeds with a molecular orientation normal to the substrate under the conditions where re-evaporation dominates the film growth process. This growth model was confirmed by fitting the data to the Avrami equation for the two-dimensionally predetermined nucleation.
Theoretical design of molecular nanomagnets for magnetic refrigeration
Authors: Garlatti E. , Carretta S. , Schnack J. , Amoretti G. , Santini P.
Published: November 2013

Molecular nanomagnets are promising materials for very-low-temperature magnetic refrigeration due to their enhanced magnetocaloric effect. By explicitly considering Carnot refrigeration cycles, we theoretically show that the best molecules for magnetic refrigeration between T≃10 K and the sub-Kelvin region are those made of strongly ferromagnetically coupled magnetic ions, contrarily to the established belief. This recipe will provide a strong stimulus for designing new magnetic molecules for cryogenic technologies.
Completely inverted hysteresis loops: Inhomogeneity effects or experimental artifacts
Authors: Song C. , Cui B. , Yu H. Y. , Pan F.
Published: November 2013

Completely inverted hysteresis loops (IHL) are obtained by the superconducting quantum interference device with large cooling fields (>10 kOe) in (La,Sr)MnO3 films with self-assembled LaSrMnO4, an antiferromagnetic interface. Although the behaviours of measured loops show many features characteristic to the IHL, its origin, however, is not due to the exchange coupling between (La,Sr)MnO3/LaSrMnO4, an often accepted view on IHL. Instead, we demonstrate that the negative remanence arises from the hysteresis of superconducting coils, which drops abruptly when lower cooling fields are utilized. Hence the completely inverted hysteresis loops are experimental artifacts rather than previously proposed inhomogeneity effects in complicated materials.
Graphene as a high impedance surface for ultra-wideband electromagnetic waves
Authors: Aldrigo Martino , Dragoman Mircea , Costanzo Alessandra , Dragoman Daniela
Published: November 2013

The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.
Serum albumin and globulin analysis for hepatocellular carcinoma detection avoiding false-negative results from alpha-fetoprotein test negative subjects
Authors: Wang Jing , Feng Shangyuan , Lin Juqiang , Zeng Yongyi , Li Ling , Huang Zufang , Li Buhong , Zeng Haishan , Chen Rong
Published: November 2013

Surface-enhanced Raman spectroscopy (SERS) of serum albumin and globulin were employed to detect hepatocellular carcinoma (HCC). Tentative assignments of SERS bands show specific biomolecular changes associated with cancer development. These changes include a decrease in relative amounts of tryptophan, glutamine, glycine, and serine, indicating excessive consumption of amino acids for protein duplication. Principal component analysis was also introduced to analyze the obtained spectra, resulting in both diagnostic sensitivity and specificity of 100%. More importantly, it reveals that this method can detect HCC patients with alpha-fetoprotein negative test results, suggesting its great potential as a new alternative to detect HCC.
Relativistic electron acceleration by oblique whistler waves
Authors: Yoon Peter H. , Pandey Vinay S. , Lee Dong-Hun
Published: November 2013

Test-particle simulations of electrons interacting with finite-amplitude, obliquely propagating whistler waves are carried out in order to investigate the acceleration of relativistic electrons by these waves. According to the present findings, an efficient acceleration of relativistic electrons requires a narrow range of oblique propagation angles, close to the whistler resonance cone angle, when the wave amplitude is held constant at relatively low value. For a constant wave propagation angle, it is found that a range of oblique whistler wave amplitudes permits the acceleration of relativistic electrons to O(MeV) energies. An initial distribution of test electrons is shown to form a power-law distribution when plotted in energy space. It is also found that the acceleration is largely uniform in electron pitch-angle space.
Double-metal-gate nanocrystalline Si thin film transistors with flexible threshold voltage controllability
Authors: Chiou Uio-Pu , Shieh Jia-Min , Yang Chih-Chao , Huang Wen-Hsien , Kao Yo-Tsung , Pan Fu-Ming
Published: November 2013

We fabricated nano-crystalline Si (nc-Si:H) thin-film transistors (TFTs) with a double-metal-gate structure, which showed a high electron-mobility (μFE) and adjustable threshold voltages (Vth). The nc-Si:H channel and source/drain (S/D) of the multilayered TFT were deposited at 375 °C by inductively coupled plasma chemical vapor deposition. The low grain-boundary defect density of the channel layer is responsible for the high μFE of 370 cm2/V-s, a steep subthreshold slope of 90 mV/decade, and a low Vth of −0.64 V. When biased with the double-gate driving mode, the device shows a tunable Vth value extending from −1 V up to 2.7 V.
Selective feeding by pelagic fish in the Belgian part of the North Sea
Authors: Van Ginderdeuren Karl , Vandendriessche Sofie , Prössler Yves , Matola Hakimu , Vincx Magda , Hostens Kris
Published: November 2013

Pelagic fish and their planktonic prey are susceptible to a changing climate, giving rise to mismatches and planktonic bottlenecks. A detailed examination of the feeding ecology of pelagic fish can provide valuable insights in the causes and consequences of these phenomena. The present study investigated the diets of both juvenile and adult herring, sprat, horse mackerel, and adult mackerel in the Belgian part of the North Sea (BPNS) in relation to the distribution of zooplankton and ambient abiotic conditions. A study sampling pelagic fish and zooplankton simultaneously every month during consecutive years, and spanning nearshore to offshore sampling locations, is unprecedented in the southern North Sea. In all, 71 prey taxa were found in 725 stomachs of fish gathered at ten stations, sampled monthly in 2009 and 2010. The proportion of fish with empty stomachs was low (11%), and the number of prey species ranged from 0 to 21 sp. per stomach. The diet of herring and sprat was dominated by calanoid copepods, but herring stomachs also contained many decapod larvae, amphipods, cumaceans, and mysids. Mackerel added sandeels to an otherwise planktivorous diet. Horse mackerel consumed both benthic and pelagic prey. The highest frequency of occurrence in the stomachs was observed for the calanoid copepods Temora longicornis (33 408 of all 55 004 prey items identified) and Centropages hamatus (5003 times found). The fullness index ranged between 0 and 20.6, and averaged highest for sprat (0.86), followed by herring (0.60), horse mackerel (0.26), and mackerel (0.24). We observed a different composition of zooplankton species and life stages in the plankton samples compared with those in the fish stomachs. More adult and female copepods were eaten than the plankton samples would suggest. Also, the calanoid copepod Acartia clausi, the most common calanoid species in the BPNS, was barely eaten, as was the case for fish eggs and larvae, and for common planktonic species known to be preyed upon elsewhere (e.g. Oikopleura dioica, Evadne nordmanni, Euterpina acutifrons). Additionally, plankton densities averaged highest in spring and at midshore (20–30 km from shore) stations, but fullness index was highest nearshore (<12 km from shore) and (apart from sprat) in summer. A significant correlation between fullness index and total density of planktonic prey species was not observed, indicating that zooplankton densities were not restrictive. Yet the fact that more than 100 plankton species occurred in the plankton samples and just two of these (T. longicornis and C. hamatus) accounted for nearly three-quarters of all ingested prey items leads us to conclude that even minor changes in the ecology or phenology of these dominant zooplankters could have profound effects on pelagic fish stocks.
The short-term impacts of implementing catch quotas and a discard ban on English North Sea otter trawlers
Authors: Condie Harriet M. , Catchpole Thomas L. , Grant Alastair
Published: November 2013

A key objective of the European Union's Common Fisheries Policy reforms is the elimination of discards and a reduction in unwanted catches. Combining a discard ban with catch quotas, where all fish, independent of size, count towards quotas could create economic incentives for more selective fishing, reducing unwanted catches. We use fishing activities data from English North Sea otter trawlers to examine the impact of these measures on this fleet. Initial impacts depend on the scale of increase and distribution of quotas and are unevenly distributed, depending on catch and discard characteristics of vessels. Selective fishing will be rewarded as vessels that currently have low discards could increase catches and profits. Fishing by less selective vessels will be curtailed, reducing profits by 1–14%. This could be partially mitigated through reducing regulated catches but will require changes to fishing patterns as using currently available selective fishing gears may impact on profitability. So, catch quotas and a discard ban create strong incentives for more selective fishing practices, but also for non-compliance with full documentation of catches. A high level of monitoring and enforcement will be required to ensure that fishers improve profitability through more selective fishing practices rather than illegal discarding.
A Kozai-resonating Earth quasi-satellite
Authors: Connors M.
Published: November 2013

The recently discovered asteroid 2013 LX28 is in 1:1 resonance with Earth, but has large eccentricity and inclination. These lead to unusual dynamics in which the Kozai resonance plays a large role on long time-scales, while interaction with the terrestrial planets causes shorter term orbital changes. For the nominal orbit, an interaction with Venus changed the nature of the Kozai resonance and injected the asteroid into resonance with Earth. Despite frequent planetary encounters, the nominal orbit shows remarkable stability. Recovery prospects for this object are excellent, so that investigation of its remarkable properties should be able to proceed on a firmer observational base in future.
Constraining new fundamental physics with multiwavelength astrometry
Authors: Egorov Pavel , Guzinin Maxim , Hakobyan Hayk , Troitsky Sergey
Published: November 2013

While the deflection of light is achromatic in General Relativity, it is not always so in several new-physics models (e.g. certain quantum-gravity and string-inspired models, models with non-minimal photon–gravity coupling or with massive photon, etc.). We discuss how parameters of these models may be constrained by precise astrometry at different wavelengths. From published observations of the gravitational lens MG J2016+112, we obtain world-best limits on chromatic gravitational deflection of light (and the unique limit on the photon mass relevant for distance scales >Mpc). We also outline prospects for further improvement of these limits.