bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFICIENTLY GENERATED SPACES OF CLASSICAL SIEGEL MODULAR FORMS AND THE BÖCHERER CONJECTURE
Authors: RAUM MARTIN
Published: April 2011

We state and verify up to weight 172 a conjecture on the existence of a certain generating set for spaces of classical Siegel modular forms. This conjecture is particularly useful for calculations involving Fourier expansions. Using this generating set, we verify the Böcherer conjecture for nonrational eigenforms and discriminants with class number greater than one. As a further application we verify another conjecture for weights up to 150 and investigate an analog of the Victor–Miller basis. Additionally, we describe some arithmetic properties of the basis we found.
Evidence-Based Practice for Children With Speech Sound Disorders: Part 1 Narrative Review
Authors: Baker Elise , McLeod Sharynne
Published: April 2011

Purpose

This article provides a comprehensive narrative review of intervention studies for children with speech sound disorders (SSD). Its companion paper (Baker & McLeod, 2011) provides a tutorial and clinical example of how speech-language pathologists (SLPs) can engage in evidence-based practice (EBP) for this clinical population.

Method

Studies reporting speech sound intervention for children with SSDs published from 1979 to 2009 were identified and coded.

Results

One hundred thirty-four intervention studies were identified. Intervention typically was conducted by an SLP in a one-to-one individual format for 30- to 60-min sessions 2 to 3 times per week. Total duration of intervention (from assessment to discharge) was reported for 10 studies and ranged from 3 to 46 months. Most studies were either Level IIb (quasi-experimental studies, 41.5%) or Level III (nonexperimental case studies, 32.6%). Single-case experimental design (29.6%) was the most frequently used experimental research design. There were 7 distinct approaches to target selection and 46 distinct intervention approaches, with 23 described in more than 1 publication. Each approach was associated with varying quantities and levels of evidence, according to research design.

Conclusion

Collaborative research reflecting higher levels of evidence using rigorous experimental designs is needed to compare the relative benefits of different intervention approaches.
Assessment and Treatment of Working Memory Deficits in School-Age Children: The Role of the Speech-Language Pathologist
Authors: Boudreau Donna , Costanza-Smith Amy
Published: April 2011

Purpose

To review research addressing the relationship of working memory (WM) to language development and academic functioning and to consider the role of the speech-language pathologist (SLP) in assessment and intervention of WM difficulties in school-age children.

Method

Aspects of WM critical to language acquisition and academic success are defined, and the importance of WM to language development and learning is discussed. Subsequently, strategies for assessing WM skills in children are presented. Following a discussion regarding the assessment of WM demands in the classroom, intervention strategies are provided.

Results

Children with poor WM skills are likely to experience significant difficulty in academic settings. Evidence-based strategies for both reducing WM demands and improving functional WM skills are reviewed.

Conclusion

Research to date has documented that children with language impairments frequently have poor WM skills. SLPs can support poor WM skills by considering both modifications to the environment and child-enacted knowledge and skills, which may serve to reduce the impact of poor WM skills on learning and academic success.
Functional Seating for School-Age Children With Cerebral Palsy: An Evidence-Based Tutorial
Authors: Costigan F. Aileen , Light Janice
Published: April 2011

Purpose

This tutorial is designed to teach speech-language pathologists (SLPs) best practices to support functional seating of children with cerebral palsy (CP) in the classroom and in school-based therapy sessions. This tutorial teaches SLPs to (a) recognize the positive effects of seating intervention, (b) identify the characteristics of functional seating that may produce these positive effects, and (c) realize their role in supporting functional seating for school-age children with CP.

Method

The research reporting positive effects of seating intervention for school-age children with CP is presented according to theInternational Classification of Functioning, Disability and Health(World Health Organization, 2001). Recommended guidelines for functional seating for school-age children with CP are gleaned from the research evidence. The specific role of the SLP in providing functional seating for children with CP is then discussed.

Conclusion

Seating intervention may produce positive body structure and function, activities, and participation effects for school-age children with CP when appropriate equipment is provided for weight bearing, the pelvis is positioned for stability and mobility, and the body is properly aligned. SLPs can support functional seating for school-age children with CP by communicating with professionals with seating expertise and by invoking and monitoring recommended guidelines for children with basic and complex seating needs, respectively.
Expository Language Skills of Young School-Age Children
Authors: Westerveld Marleen F. , Moran Catherine A.
Published: April 2011

Purpose

This research investigated the expository language skills of young school-age children with the ultimate aim of obtaining normative data for clinical practice. Specifically, this study examined (a) the level of expository language performance of 6- and 7-year-old children with typical development and (b) age-related differences between young and older school-age children.

Method

Expository discourse was elicited from two groups of children using the favorite game or sport (FGS) task. Performance of the younger age group (
n
= 61), age 6;0 (years;months) to 7;11, was compared to that of a group of twenty 11-year-old children from an earlier study. Samples were analyzed on measures of verbal productivity, syntactic complexity, grammatical accuracy, and verbal fluency.

Results

The FGS task was effective in eliciting text-level discourse from young school-age children. These children produced discourse that resulted in a fairly normal distribution across some of the language production measures. Age-related differences were observed on measures of verbal productivity, grammatical accuracy, and verbal fluency, but not on syntactic complexity.

Conclusion

The findings suggest that expository discourse sampling may be a useful addition to a language assessment protocol, even for very young school-age children.
Cell-enclosing gelatin-based microcapsule production for tissue engineering using a microfluidic flow-focusing system
Authors: Sakai Shinji , Ito Sho , Inagaki Hitomi , Hirose Keisuke , Matsuyama Tomohiro , Taya Masahito , Kawakami Koei
Published: April 2011

Gelatin-based microcapsule production using a microfluidic system and the feasibility of the resultant microcapsules for constructing spherical tissues surrounded by heterogeneous cells were studied. The first cell-encapsulation and subsequent cell-enclosing microparticle encapsulation were achieved using a microfluidic flow-focusing droplet production system. A hollow-core structure of about 150 μm in diameter was developed by incubating the resultant microparticles at 37 °C, which induced thermal melting of the enclosed unmodified gelatin microparticles. Mammalian cells filled the hollow-cores after 4 days of incubation. A cell layer on the cell-enclosing microcapsules was developed by simply suspending the microcapsules in medium containing adherent fibroblast cells. This method may prove useful for the generation of gelatin microcapsules using a microfluidic system for formation of artificial tissue constructs.
Aqueous biphasic microprinting approach to tissue engineering
Authors: Tavana Hossein , Takayama Shuichi
Published: April 2011

We summarize a recently developed microtechnology for printing biomaterials on biological surfaces. The technique is based on the use of immiscible aqueous solutions of two biopolymers and allows spatially defined placement of cells and biomolecules suspended in the denser aqueous phase on existing cell layers and extracellular matrix hydrogel surfaces maintained in the second phase. Printing takes place due to an extremely small interfacial tension and density difference between the two aqueous phases. The contact-free printing process ensures that both printed cells and the underlying cell monolayer maintain full viability and functionality. The technique accommodates both arbitrarily shaped patterns and microarrays of cells and bioreagents. The capability to print cells and small molecules on existing cell layers enables unique interrogations of the effects of cell-cell and cell-material interaction on cell fate and function. Furthermore, the very gentle conditions and the ability to directly pattern nongel embedded cells over cells make this technology appealing to tissue engineering applications where patterned multicellar organization with minimal scaffolding materials is needed, such as in dense tissues of the skeletal muscle and liver.
IUPAC-NIST Solubility Data Series. 90. Hydroxybenzoic Acid Derivatives in Binary, Ternary, and Multicomponent Systems. Part I. Hydroxybenzoic Acids, Hydroxybenzoates, and Hydroxybenzoic Acid Salts in Water and Aqueous Systems
Authors: Goto Rensuke , Fukuda Hiroshi , Königsberger Erich , Königsberger Lan-Chi
Published: April 2011

The solubility data for well-defined binary, ternary, and multicomponent systems of solid-liquid type are reviewed. One component, which is 2-, 3-, and 4-hydroxybenzoic acids, 4-hydroxybenzoate alkyl esters (parabens), or hydroxybenzoic acid salts, is in the solid state at room temperature and another component is liquid water, meaning that all of the systems are aqueous solutions. The ternary or multicomponent systems include organic substances of various classes (hydrocarbons of several structural types, halogenated hydrocarbons, alcohols, acids, ethers, esters, amides, and surfactants) or inorganic substances. Systems reported in the primary literature from 1898 through 2000 are compiled. For seven systems, sufficient binary data for hydroxybenzoic acids or parabens in water are available to allow critical evaluation. Almost all data are expressed as mass and mole fractions as well as the originally reported units, while some data are expressed as molar concentration.
Analyses of antigen dependency networks unveil immune system reorganization between birth and adulthood
Authors: Madi Asaf , Kenett Dror Y. , Bransburg-Zabary Sharron , Merbl Yifat , Quintana Francisco J. , Boccaletti Stefano , Tauber Alfred I. , Cohen Irun R. , Ben-Jacob Eshel
Published: April 2011

Much effort has been devoted to assess the importance of nodes in complex biological networks (such as gene transcriptional regulatory networks, protein interaction networks, and neural networks). Examples of commonly used measures of node importance include node degree, node centrality, and node vulnerability score (the effect of the node deletion on the network efficiency). Here, we present a new approach to compute and investigate the mutual dependencies between network nodes from the matrices of node-node correlations. To this end, we first define the dependency of node i on node j (or the influence of node j on node i), D(i, j) as the average over all nodes k of the difference between the i − k correlation and the partial correlations between these nodes with respect to node j. Note that the dependencies, D(i, j) define a directed weighted matrix, since, in general, D(i, j) differs from D( j, i). For this reason, many of the commonly used measures of node importance, such as node centrality, cannot be used. Hence, to assess the node importance of the dependency networks, we define the system level influence (SLI) of antigen j, SLI( j) as the sum of the influence of j on all other antigens i. Next, we define the system level influence or the influence score of antigen j, SLI( j) as the sum of D(i, j) over all nodes i. We introduce the new approach and demonstrate that it can unveil important biological information in the context of the immune system. More specifically, we investigated antigen dependency networks computed from antigen microarray data of autoantibody reactivity of IgM and IgG isotypes present in the sera of ten mothers and their newborns. We found that the analysis was able to unveil that there is only a subset of antigens that have high influence scores (SLI) common both to the mothers and newborns. Networks comparison in terms of modularity (using the Newman’s algorithm) and of topology (measured by the divergence rate) revealed that, at birth, the IgG networks exhibit a more profound global reorganization while the IgM networks exhibit a more profound local reorganization. During immune system development, the modularity of the IgG network increases and becomes comparable to that of the IgM networks at adulthood. We also found the existence of several conserved IgG and IgM network motifs between the maternal and newborns networks, which might retain network information as our immune system develops. If correct, these findings provide a convincing demonstration of the effectiveness of the new approach to unveil most significant biological information. Whereas we have introduced the new approach within the context of the immune system, it is expected to be effective in the studies of other complex biological social, financial, and manmade networks.
Electric field tunable magnetic properties of lead-free Na0.5Bi0.5TiO3/CoFe2O4 multiferroic composites
Authors: Narendra Babu S. , Gi Min Seong , Malkinski Leszek
Published: April 2011

Lead-free multiferroic particulate composites of Na0.5Bi0.5TiO3 (NBT) and CoFe2O4 (CFO) have been synthesized by solid-state sintering method. A systematic study of structural, magnetic and magnetoelectric (ME) properties is undertaken. Structural and morphology studies carried out by x-ray diffraction and field emission scanning electron microscopy indicate formation of single phase for parent phases and presence of both phases in the composites. Magnetic properties are investigated using vibrating sample magnetometer and ferromagnetic resonance (FMR) measurements at room temperature. Strong ME coupling is demonstrated in NBT-CFO 70-30 mol% composite by an electrostatically tunable FMR field shift up to 428 Oe (at E = 3.9 kV/cm), which increases to a large value of 640 Oe at E = 6.8 kV/cm. Furthermore, these lead-free multiferroic composites exhibiting electrostatically induced magnetic resonance field at microwave frequencies provide great opportunities for electric field tunable microwave devices.
Biochip/laser cell deposition system to assess polarized axonal growth from single neurons and neuron/glia pairs in microchannels with novel asymmetrical geometries
Authors: Pirlo R. K. , Sweeney A. J. , Ringeisen B. R. , Kindy M. , Gao B. Z.
Published: April 2011

Axon path-finding plays an important role in normal and pathogenic brain development as well as in neurological regenerative medicine. In both scenarios, axonal growth is influenced by the microenvironment including the soluble molecules and contact-mediated signaling from guiding cells and cellular matrix. Microfluidic devices are a powerful tool for creating a microenvironment at the single cell level. In this paper, an asymmetrical-channel-based biochip, which can be later incorporated into microfluidic devices for neuronal network study, was developed to investigate geometric as well as supporting cell control of polarized axonal growth in forming a defined neuronal circuitry. A laser cell deposition system was used to place single cells, including neuron-glia pairs, into specific microwells of the device, enabling axonal growth without the influence of cytophilic/phobic surface patterns. Phase microscopy showed that a novel “snag” channel structure influenced axonal growth in the intended direction 4:1 over the opposite direction. In heterotypic experiments, glial cell influence over the axonal growth path was observed with time-lapse microscopy. Thus, it is shown that single cell and heterotypic neuronal path-finding models can be developed in laser patterned biochips.
Computational design optimization for microfluidic magnetophoresis
Authors: Plouffe Brian D. , Lewis Laura H. , Murthy Shashi K.
Published: April 2011

Current macro- and microfluidic approaches for the isolation of mammalian cells are limited in both efficiency and purity. In order to design a robust platform for the enumeration of a target cell population, high collection efficiencies are required. Additionally, the ability to isolate pure populations with minimal biological perturbation and efficient off-chip recovery will enable subcellular analyses of these cells for applications in personalized medicine. Here, a rational design approach for a simple and efficient device that isolates target cell populations via magnetic tagging is presented. In this work, two magnetophoretic microfluidic device designs are described, with optimized dimensions and operating conditions determined from a force balance equation that considers two dominant and opposing driving forces exerted on a magnetic-particle-tagged cell, namely, magnetic and viscous drag. Quantitative design criteria for an electromagnetic field displacement-based approach are presented, wherein target cells labeled with commercial magnetic microparticles flowing in a central sample stream are shifted laterally into a collection stream. Furthermore, the final device design is constrained to fit on standard rectangular glass coverslip (60 (L)×24 (W)×0.15 (H) mm3) to accommodate small sample volume and point-of-care design considerations. The anticipated performance of the device is examined via a parametric analysis of several key variables within the model. It is observed that minimal currents (<500 mA) are required to generate magnetic fields sufficient to separate cells from the sample streams flowing at rate as high as 7 ml/h, comparable to the performance of current state-of-the-art magnet-activated cell sorting systems currently used in clinical settings. Experimental validation of the presented model illustrates that a device designed according to the derived rational optimization can effectively isolate (∼100%) a magnetic-particle-tagged cell population from a homogeneous suspension even in a low abundance. Overall, this design analysis provides a rational basis to select the operating conditions, including chamber and wire geometry, flow rates, and applied currents, for a magnetic-microfluidic cell separation device.
Node importance for dynamical process on networks: A multiscale characterization
Authors: Zhang Jie , Xu Xiao-Ke , Li Ping , Zhang Kai , Small Michael
Published: April 2011

Defining the importance of nodes in a complex network has been a fundamental problem in analyzing the structural organization of a network, as well as the dynamical processes on it. Traditionally, the measures of node importance usually depend either on the local neighborhood or global properties of a network. Many real-world networks, however, demonstrate finely detailed structure at various organization levels, such as hierarchy and modularity. In this paper, we propose a multiscale node-importance measure that can characterize the importance of the nodes at varying topological scale. This is achieved by introducing a kernel function whose bandwidth dictates the ranges of interaction, and meanwhile, by taking into account the interactions from all the paths a node is involved. We demonstrate that the scale here is closely related to the physical parameters of the dynamical processes on networks, and that our node-importance measure can characterize more precisely the node influence under different physical parameters of the dynamical process. We use epidemic spreading on networks as an example to show that our multiscale node-importance measure is more effective than other measures.
Reducing audible noise for distribution transformer with HB1 amorphous core
Authors: Chang Yeong-Hwa , Hsu Chang-Hung , Lin Hung-Wei , Tseng Ching-Pei
Published: April 2011

In this paper, the way to reduce the audible noise of a distribution transformer is presented by incorporating a newly developed transformer core and a rigid-structure tank. The vibrations related tothe core structure and tank frame are considered, so that a distribution transformer with accelerometers mounted on the internal core and external tank, respectively, is addressed. In practice, the core with a new joint structure and the tank with a strong rigid-frame (H-type) are applied to a single-phase amorphous HB1-cored transformer with capacity 167 kVA for performance verification. Finally, a personal computer-based data acquisition platform is setup for signal measurement and processing. Experimental results demonstrate that the HB1 amorphous-cored transformer with the proposed core joint and rigid-structure tank can be performed well in the aspect of audible noise reduction.
A midsize tokamak as a fast track to burning plasmas
Authors: Mazzucato E.
Published: April 2011

This paper describes the conceptual design of a midsize tokamak as a fast track to the investigation of burning plasmas. It is shown that it could reach large values of energy gain (≥ 10) with only a modest improvement in confinement over the scaling that was used for designing the International Thermonuclear Experimental Reactor (ITER). This can be achieved by operating in a low plasma recycling regime that experiments indicate can lead to improved plasma confinement. The possibility of reaching the necessary conditions of low recycling using a different magnetic divertor from those currently employed in present experiments is discussed.
Enantiotopic discrimination in the deuterium NMR spectrum of solutes with S4 symmetry in chiral liquid crystals
Authors: Aroulanda Christie , Zimmermann Herbert , Luz Zeev , Lesot Philippe
Published: April 2011

Enantiotopic discrimination in the NMR spectra of prochiral rigid solutes in chiral liquid crystals (CLC), by the ordering mechanism, is limited to molecules possessing one of the four, so called, “allowed” symmetries, D2d, C2v, Cs, and S4. So far, such spectral discrimination was demonstrated only for solutes possessing one of the first three symmetries. In this work, we present deuterium NMR measurements on a rigid S4 compound dissolved in a chiral nematic solvent and demonstrate, for the first time, enantiotopic discrimination in such symmetry. The measurements were performed on the isotopically normal icosane derivative (1) and on its isotopomer (1-d8), specifically deuterated in its four core methylene groups. As a CLC solvent, a lyotropic mesophase, consisting of a solution of poly-γ-benzyl-L-glutamate (PBLG) in pyridine, was employed. For comparison with a corresponding achiral liquid crystal (ALC) solvent, a solution of a racemic mixture of poly-γ-benzylglutamate (PBG) of similar composition in the same co-solvent was used. The spectra were recorded at 92.1 MHz using the 2D Q-COSY Fz sequence with proton decoupling. In the CLC solvents they exhibited clear discrimination due to different enantiotopic sites, with components displaced symmetrically, at frequencies below and above those in the corresponding ALC, as expected for discrimination by ordering. Two procedures were employed for correlating the enantiotopic sites in the CLC spectra. For 1-d8 the dipolar cross-peaks in a 2D 2H-2H COSY-90 experiment provided identification of signals belonging to the same methylene (and hence the same enantiotopic) groups. For 1 the correlation was achieved using a least-square-deviation fitting of the experimental quadrupole splittings with respect to those expected from the molecular geometry. These results, with appropriate symmetry considerations were used to determine the symmetric (Szz) and antisymmetric (Sxy and Sxx−Syy) components of the Saupe ordering matrix. Interpretation of the NMR spectra of prochiral solutes in CLC suffers from the ambiguity in identifying the signals with specific enantiotopic groups. For this reason only the relative (but not the absolute) signs of the antisymmetric elements of the ordering matrix can be determined. For the S4 group this leads to sign ambiguity in the rhombic term in the diagonalized ordering matrix. Similar (but not identical) ambiguities occur for solutes belonging to the other allowed groups. In a concluding section of the paper, the ambiguities in the antisymmetric order parameters for the various allowed groups are compared and their physical meaning are discussed.
Microfluidics-based devices: New tools for studying cancer and cancer stem cell migration
Authors: Huang Yu , Agrawal Basheal , Sun Dandan , Kuo John S. , Williams Justin C.
Published: April 2011

Cell movement is highly sensitive to stimuli from the extracellular matrix and media. Receptors on the plasma membrane in cells can activate signal transduction pathways that change the mechanical behavior of a cell by reorganizing motion-related organelles. Cancer cells change their migration mechanisms in response to different environments more robustly than noncancer cells. Therefore, therapeutic approaches to immobilize cancer cells via inhibition of the related signal transduction pathways rely on a better understanding of cell migration mechanisms. In recent years, engineers have been working with biologists to apply microfluidics technology to study cell migration. As opposed to conventional cultures on dishes, microfluidics deals with the manipulation of fluids that are geometrically constrained to a submillimeter scale. Such small scales offer a number of advantages including cost effectiveness, low consumption of reagents, high sensitivity, high spatiotemporal resolution, and laminar flow. Therefore, microfluidics has a potential as a new platform to study cell migration. In this review, we summarized recent progress on the application of microfluidics in cancer and other cell migration researches. These studies have enhanced our understanding of cell migration and cancer invasion as well as their responses to subtle variations in their microenvironment. We hope that this review will serve as an interdisciplinary guidance for both biologists and engineers as they further develop the microfluidic toolbox toward applications in cancer research.
Simulations of Richtmyer–Meshkov instabilities in planar shock-tube experiments
Authors: Grinstein F. F. , Gowardhan A. A. , Wachtor A. J.
Published: April 2011

In the large eddy simulation (LES) approach, large-scale energy-containing structures are resolved, smaller structures are filtered out, and unresolved subgrid effects are modeled. Extensive recent work has demonstrated that predictive under-resolved simulations of the velocity fields in turbulent flows are possible without resorting to explicit subgrid models when using a class of physics-capturing high-resolution finite-volume numerical algorithms. This strategy is denoted as implicit LES (ILES). Tests in fundamental applications ranging from canonical to complex flows indicate that ILES is competitive with conventional LES in the LES realm proper—flows driven by large-scale features. The performance of ILES in the substantially more difficult problem of under-resolved material mixing driven by under-resolved velocity fields and initial conditions is a focus of the present work. Progress in addressing relevant resolution issues in studies of mixing driven by Richtmyer–Meshkov instabilities in planar shock-tube laboratory experiments is reported. Our particular focus is devoted to the initial material interface characterization and modeling difficulties, and effects of initial condition specifics (resolved spectral content) on transitional and late-time turbulent mixing—which were not previously addressed.
The influence of Fe content on the magnetic and electromagnetic characteristics for Fex(CoNi)1−x ternary alloy nanoparticles
Authors: Yan S. J. , Zhen L. , Xu C. Y. , Jiang J. T. , Shao W. Z. , Lu L. , Tang J.
Published: April 2011

Fex(CoNi)1−x (x = 0.14, 0.20, 0.25) ternary alloy nanoparticles were fabricated by a self-catalyzed reduction method at a low temperature. The investigation of static magnetic properties revealed both saturation magnetization and coercive force enhanced with increasing Fe content. By dispersing alloy nanoparticles into paraffin matrix homogeneously, the electromagnetic properties of them were investigated experimentally and the electromagnetic absorption performances were calculated according to transmission line theory. Significant dielectric relaxation was found in the low Fe content sample, which is dominant in dielectric loss. The magnetic loss was attributed to natural resonance and the resonance peaks’ shift to high frequency region with increasing Fecontent. The enhanced electromagnetic absorption performances were obtained by adjusting Fe content to balance electromagnetic parameters, because the electromagnetic parameters can be varied by structural and magnetic properties.
Brillouin scattering of H2O ice to megabar pressures
Authors: Ahart Muhtar , Somayazulu Maddury , Gramsch Stephen A. , Boehler Reinhard , Mao Ho-kwang , Hemley Russell J.
Published: April 2011

The sound velocity in polycrystalline ice was measured as a function of pressure at room temperature to 100 GPa, through the phase field of ice VII and crossing the ice X transition, by Brillouin scattering in order to examine the elasticity, compression mechanism, and structural transitions in this pressure range. In particular, we focused on previously proposed phase transitions below 60 GPa. Throughout this pressure range, we find no evidence for anomalous changes in compressibility, and the sound velocities and elastic moduli do not exhibit measurable discontinuous shifts with pressure. Subtle changes in the pressure dependence of the bulk modulus at intermediate pressures can be attributed to high shear stresses at these compressions. The C11 and C12 moduli are consistent with previously reported results to 40 GPa and increase monotonically at higher pressures.
Mathematical model II. Basic particle and special relativity
Authors: Gadre Nitin Ramchandra
Published: April 2011

The basic particle electron obeys various theories like electrodynamics, quantum mechanics and special relativity. Particle under different experimental conditions behaves differently, allowing us to observe different characteristics which become basis for these theories. In this paper, we try to find out the requirements of the special relativity and suggest a mathematical particle model which can satisfy these requirements. The basic presumption is that the particle should have some structural characteristics which make the particle obey the postulates of these theories. As it is experimentally ‘difficult’ to find the structure of basic particle electron we make a mathematical attempt. We call this model as logically and mathematically probable structure of the basic particle, electron.
Structure and magnetism of MnAu nanoclusters
Authors: Wei X. , Roy D. Le , Skomski R. , Li X. Z. , Sun Z. , Shield J. E. , Kramer M. J. , Sellmyer D. J.
Published: April 2011

Equiatomic MnAu clusters with average sizes of 4 and 10 nm are produced by inert-gas condensation. As-produced clusters are used to form both dense cluster films and films with clusters embedded in a W matrix with a cluster volume fraction of 25%. Both structure and magnetism are size-dependent. Structural analysis of the 10 nm clusters indicate a distorted tetragonal body-centered cubic structure with lattice parameters a = 0.315 and c = 0.329 nm. The 4 nm clusters have a partially ordered tetragonal L10 structure with lattice parameters a = 0.410 nm and c = 0.395 nm. Magnetic properties of the clusters show evidence at low temperatures of mixed ferromagnetic and antiferromagnetic interactions and ordering as well as paramagnetic spins. Saturation moments are as large as 0.54 µB per average Mn atom. The results are compared with earlier theoretical calculations on bulk MnAu.
Nanocrystalline SmCo5 magnets with laminated structure and increased electrical resistivity
Authors: Gabay A. M. , Marinescu-Jasinski M. , Li W. F. , Liu J. F. , Hadjipanayis G. C.
Published: April 2011

Magnetically isotropic Sm–Co permanent magnets with anisotropic electrical conductivity were produced by hot-pressing SmCo5 ultrathin flakes with or without insulating additions of mica, MoS2, CaF2, and B2O3. The laminated structures of the magnets were assured by the natural packing of the flakes in the die. In the additive-free magnets, the resistivity is increased due to oxidized flake boundaries. Additives with platelet-shaped particles (mica, MoS2) and especially those with low-melting temperature (B2O3) form more continuous insulating layers. On the other hand, the CaF2 additive does not react with the magnetic Sm–Co phase. The characteristic values of the maximum energy product and electrical resistivity, measured in orthogonal directions, were 9.7 MG Oe and 130 μΩ cm for the additive-free magnet, 5.7 MG Oe and 640 μΩ cm for the magnet made with 2 wt. % B2O3 and 5.7 MG Oe and 330 μΩ cm for the magnet made with 10 wt. % CaF2.
Spin flip of a single anisotropic magnetic impurity in four-terminal Landauer setup with Rashba spin-orbit coupling
Authors: Su Yu-Hsin , Chen Son-Hsien , Chen Kuo-Wei , Chen Chien-Liang , Chang Ching-Ray
Published: April 2011

The mean-field-assisted Landauer–Keldysh formalism is employed to study the flip of an impurity spin under a uniaxial anisotropic field in two-dimensional electron gas with Rashba spin-orbit coupling. The spin-flip process with uniaxial anisotropic axis set to three different directions is investigated in a four-terminal Landauer setup. We show that the spin flip follows a three-dimensional trajectory rather than in-plane motion. As bias voltage changes sign, the impurity spin will flip from one saturated state to another and move along a different trajectory, depending on the chosen initial saturated state.
Controlled growth of aligned α-helical-polypeptide brushes for tunable electrical conductivity
Authors: Wu Jen-Chia , Chen Chia-Chun , Chen Kuei-Hsien , Chang Ying-Chih
Published: April 2011

Polypeptide based molecular diode with high rectification ratio (∼122 at ±0.422 V) is formed by controlling molecular order and orientation. A film of tethered poly(γ-benzyl-L-glutamate) (PBLG) with high degree of molecular orientation was formed by solvent pair (good/bad) treatment. I-V characterization of the well aligned polypeptides showed that the rectification ratio of PBLG was sufficiently large for potential diode and transistor applications.
The geometrical origin of the strain-twist coupling in double helices
Authors: Olsen Kasper , Bohr Jakob
Published: April 2011

A simple geometrical explanation for the counterintuitive phenomenon when twist leads to extension in double helices is presented. The coupling between strain and twist is investigated using a tubular description. It is shown that the relation between strain and rotation is universal and depends only on the pitch angle. For pitch angles below 39.4° strain leads to further winding, while for larger pitch angles strain leads to unwinding. The zero-twist structure, with a pitch angle of 39.4°, is at the unique point between winding and unwinding and independent of the mechanical properties of the double helix. The existence of zero-twist structures, i.e. structures that display neither winding, nor unwinding under strain is discussed. Close-packed double helices are shown to extend rather than shorten when twisted. Numerical estimates of this elongation upon winding are given for DNA, chromatin, and RNA.
Characterization of stearic acid adsorption on Ni(111) surface by experimental and first-principles study approach
Authors: Liang S. H. , Yu T. , Liu D. P. , Wang W. X. , Wang Y. P. , Han X. F.
Published: April 2011

Long-chain alkanoic acids usually form close-packed monolayer films with alkyl chains highly oriented on substrates. Previous studies have reported the adsorption of stearic acid on gold, aluminum, copper, silver, and aluminum oxide. However, there are no reports of stearic acid adsorption on magnetic metals. In this work, the characterization of stearic acid adsorbed on Ni(111) surface has been studied experimentally and with first-principles calculation. The results suggest that the stearic acid is chemically adsorbed on the Ni(111) surface via a bidentate interaction with a distance of about 1.8 Å. Besides this, we have also obtained results for the charge transfer and magnetic proximity effect.
Postbuckling analysis of nanowires with surface effects
Authors: Wang Gang-Feng , Yang Fan
Published: April 2011

Nanowires have many technological applications as manipulators, force sensors and probes in nano-electromechanical systems. With the increasing ratio of surface area to bulk, surface effects play an important role in the mechanical response of nanowires. In this paper, we consider the influence of residual surface stress and surface elasticity on the postbuckling state of nanowires. The geometric nonlinear finite deformation theory is adopted to describe the large deflection and the midplane stretching in postbuckling, and the shooting method is employed to obtain the postbuckling path and the buckled configurations. This study might be helpful to accurately calibrate the nanowire-based force sensors and design nanowire-based devices in a wide range of applications.
Coexistence of spin glass behavior and long-range ferrimagnetic ordering in La- and Dy-doped Co ferrite
Authors: Bharathi K. Kamala , Tackett R. J. , Botez C. E. , Ramana C. V.
Published: April 2011

The structure, dc magnetization and ac susceptibility characteristics of the rare-earth (R = La,Dy) ionsubstituted cobalt-ferrites (CoO.Fe1.925La0.075O3 and CoO.Fe1.925Dy0.075O3) are evaluated. R-substituted Co-ferrites crystallize in the cubic inverse spinel phase. The irreversible temperature (Tirr) between zero field cooled (ZFC) and field cooled (FC) magnetization for CoO.Fe1.925La0.075O3 and CoO.Fe1.925Dy0.075O3 determined from the temperature variation of magnetization measurements are 283 and 292 K, respectively. The broadening of ZFC magnetization and more than one maximum indicates the coexistence of short-range ferrimagnetic clusters of different size with a long-range ferrimagnetic phase. Magnetization curves indicate no saturation up to 30 kOe suggesting the canted spin structure inside the clusters. The relaxation times of spin clusters calculated using theVogel−Fulcher law for the frequency-dependent ac susceptibility measurements are on the order of ∼10−6 s.
Micromagnetic calculation of spin transfer torque in Co/Cu multilayer nanowires
Authors: Hernández Stephanie , Tan Liwen , Stadler Bethanie J. H. , Victora R. H.
Published: April 2011

An approach for calculating spin transfer torque including interfacial scattering effects in structures consisting of multiple ferromagnet/nonmagnet (FM/NM) bilayers was developed. Using this approach, a micromagnetic analysis on structures consisting of six magnetic layers was compared to electrical measurements on electrodeposited Co/Cu multilayered nanowires. Good agreement with experiment was achieved if it was assumed that one of the layers is magnetically fixed. An array of 16 wires, each consisting of 6 FM/NM bilayers, was also micromagnetically modeled and compared to a similar experimental measurement. Both results confirm that including a wide distribution of wires results in a less uniform switching mechanism.
Silicon nanoparticle-functionalized fiberglass pads for sampling
Authors: Mantey Kevin , Nayfeh Munir H. , Al-Hreish Bahjat , Boparai Jack , Kumar Ashok , Stephenson Larry D. , Nelson Andrew J. , Alrokayan Salman A. , Abu-Salah Khalid M.
Published: April 2011

We used wet treatment to immobilize luminescent silicon nanoparticles on industrial glass fibers to impart optical and chemical functions to the fiber. Carpets or pads consisting of thousands of fibers are processed in parallel, enhancing the sensitivity of detection and the sampled volume. Treated pads exhibit strong luminescence, characteristic of the luminescence of the particles; showing no shift, broadening, or reduction of quantum efficiency. We demonstrate that drawing material by the pad due to physical adsorption can be reversed. We also demonstrate that allylamine can be covalently attached by photoinduced irradiation reactions, which results in imprinting the amine emission spectrum, providing spectral recognition. The imprint accompanied with a blue-shifting of the luminescence spectrum of the probe, allowing examination of the effect of termination on the nanoparticle structure. The shift is found to be consistent with an increase in the bandgap of the Si nanoparticle and is consistent with Quantum Monte Carlo calculations. In addition to sampling, the nano probe pad has the potential to enable a variety of biomedical applications through subsequent attachment.
Characterization of impurity confinement on Alcator C-Mod using a multi-pulse laser blow-off system
Authors: Howard N. T. , Greenwald M. , Rice J. E.
Published: April 2011

A new laser blow-off system for use in impurity transport studies on Alcator C-Mod was developed and installed for the 2009 run campaign. Its design included capabilities for multiple impurity injections during a single plasma pulse and remote manipulation of the ablated spot size. The system uses a 0.68 J, Nd:YAG laser operating at up to 10 Hz coupled with the fast beam steering via a 2D piezoelectric mirror mount able to move spot locations in the 100 ms between laser pulses and a remote controllable optical train that allow ablated spot sizes to vary from ∼0.5 to 7 mm. The ability to ablate a wide range in target Z along with Alcator C-Mod's extensive diagnostic capabilities (soft x-ray, vacuum ultraviolet (VUV), charge exchange spectroscopy, etc.) allows for detailed studies of the impurity transport dependencies and mechanisms. This system has demonstrated the achievement of all its design goals including the ability for non-perturbative operation allowing for insight into underlying impurity transport processes. A detailed overview of the laser blow-off system and initial results of operation are presented. This includes an investigation into the characterization of impurity confinement in the I-mode confinement regime recently investigated on C-Mod.
Modulational instability of ion-acoustic waves in plasmas with superthermal electrons
Authors: Gharaee H. , Afghah S. , Abbasi H.
Published: April 2011

Using the reductive perturbation technique, the modulational instability of ion- acoustic waves in a plasma containing superthermal electrons is studied. It is found that the presence of superthermal electrons significantly changes the instability domain. A Lorentzian (kappa) velocity distribution function is used to model superthermal electrons. It is shown that the presence of superthermal electrons reduces the critical frequency of the modulational instability of ion-acoustic waves. Besides, due to the presence of the superthermal electrons, ion-acoustic waves are unstable on a vaster region. Moreover, the modulational instability growth rate is larger for a larger population of superthermal electrons.
Infrared absorption of CH3SO2 observed upon irradiation of a p-H2 matrix containing CH3I and SO2
Authors: Lee Yu-Fang , Lee Yuan-Pern
Published: April 2011

Irradiation with a mercury lamp at 254 nm of a p-H2 matrix containing CH3I and SO2 at 3.3 K, followed by annealing of the matrix, produced prominent features at 633.8, 917.5, 1071.1 (1072.2), 1272.5 (1273.0, 1273.6), and 1416.0 cm−1, attributable to ν11 (C−S stretching), ν10 (CH3 wagging), ν8 (SO2 symmetric stretching), ν7 (SO2 antisymmetric stretching), and ν4 (CH2 scissoring) modes of methylsulfonyl radical (CH3SO2), respectively; lines listed in parentheses are weaker lines likely associated with species in a different matrix environment. Further irradiation at 365 nm diminishes these features and produced SO2 and CH3. Additional features at 1150.1 and 1353.1 (1352.7) cm−1 are tentatively assigned to the SO2 symmetric and antisymmetric stretching modes of ISO2. These assignments are based on comparison of observed vibrational wavenumbers and 18O- and 34S-isotopic shifts with those predicted with the B3P86 method. Our results agree with the previous report of transient IR absorption bands of gaseous CH3SO2 at 1280 and 1076 cm−1. These results demonstrate that the cage effect of solid p-H2 is diminished so that CH3 radicals, produced via UV photodissociation of CH3I in situ, might react with SO2 to form CH3SO2 during irradiation and upon annealing. Observation of CH3SO2 but not CH3OSO is consistent with the theoretical predictions that only the former reactions proceed via a barrierless path.
Dissipation scales of kinetic helicities in turbulence
Authors: Lessinnes T. , Plunian F. , Stepanov R. , Carati D.
Published: April 2011

A systematic study of the influence of the viscous effect on both the spectra and the nonlinear fluxes of conserved as well as nonconserved quantities in Navier–Stokes turbulence is proposed. This analysis is used to estimate the helicity dissipation scale which is shown to coincide with the energy dissipation scale. However, it is shown using the decomposition of helicity into eigenmodes of the curl operator that viscous effects have to be taken into account for wave vectors smaller than the Kolmogorov wave number in the evolution of these eigencomponents of the helicity.
Resistance state-dependent barrier inhomogeneity and transport mechanisms in resistive-switching Pt/SrTiO3 junctions
Authors: Lee Eunsongyi , Gwon Minji , Kim Dong-Wook , Kim Hogyoung
Published: April 2011

We investigated the current–voltage (I−V) and photocurrent characteristics of Pt/Nb-doped SrTiO3 (001) single-crystal junctions that exhibit resistive-switching behaviors. The temperature-dependent I−V data and the photocurrent spectra showed that the barrier height fluctuation depended on the resistance state but the mean barrier height was nearly constant regardless of the junctions’ resistance state. In addition, local barrier height variations allowed transitions from thermionic to tunneling transport for the low-resistance state.
Magnetohydrodynamic interference with the edge pedestal motional Stark effect diagnostic on DIII-D
Authors: King J. D. , Makowski M. A. , Holcomb C. T. , Allen S. L. , Hill D. N. , La Haye R. J. , Turco F. , Petty C. C. , Van Zeeland M. A. , Rhodes T. L. , Meyer W. H. , Geer R. , Morse E. C.
Published: April 2011

Accurate measurement of internal magnetic field direction using motional Stark effect (MSE) polarimetry in the edge pedestal is desired for nearly all tokamak scenario work. A newly installed 500 kHz 32-channel digitizer on the MSE diagnostic of DIII-D allows full spectral information of the polarimeter signal to be recovered for the first time. Fourier analysis of this data has revealed magnetohydrodynamic (MHD) fluctuations in the plasma edge pedestal at ρ ⩾ 0.92. By correlating edge localized mode fluctuations seen on lock-in amplifier outputs with MSE spectrograms, it has been shown that edge pedestal tearing mode fluctuations cause interference with MSE second harmonic instrument frequencies. This interference results in unrecoverable errors in the real-time polarization angle measurement that are more than an order of magnitude larger than typical polarimeter uncertainties. These errors can cause as much as a 38% difference in local q. By using a redundant measure of the linear polarization found at the fourth harmonic photo-elastic modulator (PEM) frequency, MHD interference can be avoided. However, because of poorer signal-to-noise the fourth harmonic signal computed polarization angle shows no improvement over the MHD polluted second harmonics. MHD interference could be avoided in future edge pedestal tokamak polarimeters by utilizing PEMs with higher fundamental frequencies and a greater separation between their frequencies.