bluuebunny/crossref_metadata_2025 huggingface dataset:
Miniature coils for producing pulsed inplane magnetic fields for nanospintronics
Authors: Pawliszak Łukasz , Tekielak Maria , Zgirski Maciej
Published: March 2015

Nanospintronic and related research often requires the application of quickly rising magnetic field pulses in the plane of the studied planar structure. We have designed and fabricated sub-millimeter-sized coils capable of delivering pulses of the magnetic field up to ∼500 Oe in the plane of the sample with the rise time of the order of 10 ns. The placement of the sample above the coil allows for easy access to its surface with manipulators or light beams for, e.g., Kerr microscopy. We use the fabricated coil to drive magnetic domain walls in 1 μm wide permalloy wires and measure magnetic domain wall velocity as a function of the applied magnetic field.
Calculation of the molecular integrals with the range-separated correlation factor
Authors: Silkowski Michał , Lesiuk Michał , Moszynski Robert
Published: March 2015

Explicitly correlated quantum chemical calculations require calculations of five types of two-electron integrals beyond the standard electron repulsion integrals. We present a novel scheme, which utilises general ideas of the McMurchie-Davidson technique, to compute these integrals when the so-called “range-separated” correlation factor is used. This correlation factor combines the well-known short range behaviour resulting from the electronic cusp condition, with the exact long-range asymptotics derived for the helium atom [Lesiuk, Jeziorski, and Moszynski, J. Chem. Phys. 139, 134102 (2013)]. Almost all steps of the presented procedure are formulated recursively, so that an efficient implementation and control of the precision are possible. Additionally, the present formulation is very flexible and general, and it allows for use of an arbitrary correlation factor in the electronic structure calculations with minor or no changes.
Positive contraction mappings for classical and quantum Schrödinger systems
Authors: Georgiou Tryphon T. , Pavon Michele
Published: March 2015

The classical Schrödinger bridge seeks the most likely probability law for a diffusion process, in path space, that matches marginals at two end points in time; the likelihood is quantified by the relative entropy between the sought law and a prior. Jamison proved that the new law is obtained through a multiplicative functional transformation of the prior. This transformation is characterised by an automorphism on the space of endpoints probability measures, which has been studied by Fortet, Beurling, and others. A similar question can be raised for processes evolving in a discrete time and space as well as for processes defined over non-commutative probability spaces. The present paper builds on earlier work by Pavon and Ticozzi and begins by establishing solutions to Schrödinger systems for Markov chains. Our approach is based on the Hilbert metric and shows that the solution to the Schrödinger bridge is provided by the fixed point of a contractive map. We approach, in a similar manner, the steering of a quantum system across a quantum channel. We are able to establish existence of quantum transitions that are multiplicative functional transformations of a given Kraus map for the cases where the marginals are either uniform or pure states. As in the Markov chain case, and for uniform density matrices, the solution of the quantum bridge can be constructed from the fixed point of a certain contractive map. For arbitrary marginal densities, extensive numerical simulations indicate that iteration of a similar map leads to fixed points from which we can construct a quantum bridge. For this general case, however, a proof of convergence remains elusive.
First-principles investigation on mechanical, electronic, and thermodynamic properties of Mg2Sr under high pressure
Authors: Mao Pingli , Yu Bo , Liu Zheng , Wang Feng , Ju Yang
Published: March 2015

The structural, mechanical, electronic, and thermodynamic properties of Mg2Sr with C14-type structure under pressures ranging from 0 to 40 GPa have been systematically studied within the framework of density functional theory in this work. The results at zero pressure were in good agreement with the available theoretical and experimental values. The pressure dependence of structure and elastic constants, elastic anisotropy, Cauchy pressure, melting points, and hardness was successfully calculated and discussed. In addition, the electronic density of states (DOSs) under various pressures were investigated. Debye temperature and the dependences of thermodynamic properties on temperature and pressure were also discussed in the present paper.
Characteristics of a molybdenum X-pinch X-ray source as a probe source for X-ray diffraction studies
Authors: Zucchini F. , Bland S. N. , Chauvin C. , Combes P. , Sol D. , Loyen A. , Roques B. , Grunenwald J.
Published: March 2015

X-ray emission from a molybdenum X-pinch has been investigated as a potential probe for the high pressure states made in dynamic compression experiments. Studies were performed on a novel 300 kA, 400 ns generator which coupled the load directly to a low inductance capacitor and switch combination. The X-pinch load consisted of 4 crossed molybdenum wires of 13 μm diameter, crossed at an angle of 62°. The load height was 10 mm. An initial x-ray burst generated at the wire crossing point, radiated in the soft x-ray range (hυ < 10 keV). This was followed, 2–5 ns later, by at least one harder x-ray burst (hυ > 10 keV) whose power ranged from 1 to 7 MW. Time integrated spectral measurements showed that the harder bursts were dominated by K-alpha emission; though, a lower level, wide band continuum up to at least 30 keV was also present. Initial tests demonstrated that the source was capable of driving Laue diffraction experiments, probing uncompressed samples of LiF and aluminium.
Toward quantitative modeling of silicon phononic thermocrystals
Authors: Lacatena V. , Haras M. , Robillard J.-F. , Monfray S. , Skotnicki T. , Dubois E.
Published: March 2015

The wealth of technological patterning technologies of deca-nanometer resolution brings opportunities to artificially modulate thermal transport properties. A promising example is given by the recent concepts of "thermocrystals" or "nanophononic crystals" that introduce regular nano-scale inclusions using a pitch scale in between the thermal phonons mean free path and the electron mean free path. In such structures, the lattice thermal conductivity is reduced down to two orders of magnitude with respect to its bulk value. Beyond the promise held by these materials to overcome the well-known “electron crystal-phonon glass” dilemma faced in thermoelectrics, the quantitative prediction of their thermal conductivity poses a challenge. This work paves the way toward understanding and designing silicon nanophononic membranes by means of molecular dynamics simulation. Several systems are studied in order to distinguish the shape contribution from bulk, ultra-thin membranes (8 to 15 nm), 2D phononic crystals, and finally 2D phononic membranes. After having discussed the equilibrium properties of these structures from 300 K to 400 K, the Green-Kubo methodology is used to quantify the thermal conductivity. The results account for several experimental trends and models. It is confirmed that the thin-film geometry as well as the phononic structure act towards a reduction of the thermal conductivity. The further decrease in the phononic engineered membrane clearly demonstrates that both phenomena are cumulative. Finally, limitations of the model and further perspectives are discussed.
The similarity subgrid stresses associated to the approximate Van Cittert deconvolutions
Authors: Germano M.
Published: March 2015

In the paper, we derive directly the expressions of the subgrid stresses associated to the approximate Van Cittert deconvolutions and we discuss their similarity structure and properties.
Radiofrequency encoded angular-resolved light scattering
Authors: Buckley Brandon W. , Akbari Najva , Diebold Eric D. , Adam Jost , Jalali Bahram
Published: March 2015

The sensitive, specific, and label-free classification of microscopic cells and organisms is one of the outstanding problems in biology. Today, instruments such as the flow cytometer use a combination of light scatter measurements at two distinct angles to infer the size and internal complexity of cells at rates of more than 10 000/s. However, by examining the entire angular light scattering spectrum, it is possible to classify cells with higher resolution and specificity. Current approaches to performing these angular spectrum measurements all have significant throughput limitations, making them incompatible with other state-of-the-art flow cytometers. Here, we introduce a method for performing complete angular scattering spectrum measurements at high throughput combining techniques from the field of scattering flow-cytometry and radiofrequency communications. Termed Radiofrequency Encoded Angular-resolved Light Scattering, this technique multiplexes angular light scattering in the radiofrequency domain, such that a single photodetector captures the entire scattering spectrum from a particle over approximately 100 discrete incident angles on a single shot basis. As a proof-of-principle experiment, we use this technique to perform scattering measurements over a range of 30° from a tapered optical fiber at a scan rate of 250 kHz.
Thirty years of turnstiles and transport
Authors: Meiss J. D.
Published: March 2015

To characterize transport in a deterministic dynamical system is to compute exit time distributions from regions or transition time distributions between regions in phase space. This paper surveys the considerable progress on this problem over the past thirty years. Primary measures of transport for volume-preserving maps include the exiting and incoming fluxes to a region. For area-preserving maps, transport is impeded by curves formed from invariant manifolds that form partial barriers, e.g., stable and unstable manifolds bounding a resonance zone or cantori, the remnants of destroyed invariant tori. When the map is exact volume preserving, a Lagrangian differential form can be used to reduce the computation of fluxes to finding a difference between the actions of certain key orbits, such as homoclinic orbits to a saddle or to a cantorus. Given a partition of phase space into regions bounded by partial barriers, a Markov tree model of transport explains key observations, such as the algebraic decay of exit and recurrence distributions.
A novel claw pole memory machine for wide-speed-range applications
Authors: Jian Linni , Gong Yu , Wei Jin , Shi Yujun , Shao Ziyun , Ching T. W.
Published: March 2015

Memory machines with both high-power-density and wide-speed-range are becoming very attractive most recently. The purpose of this paper is to propose a novel type of memory machine, namely, claw pole memory machine. It engages an axially magnetized AlNiCo PM ring on the claw pole rotor to build the main magnetic flux in air-gap which is responsible for the electromechanical energy conversion. A magnetizing coil is equipped to online regulate the magnetization level of the permanent magnet ring, so as to achieve wide-speed-range operation. The operating principle is analyzed. The Preisach hysteresis model is combined with 3D finite element method to conduct performance assessment of the proposed claw pole memory machine. Calculation results demonstrate that the air-gap flux density can be readily adjusted by injecting DC pulse into the magnetizing coil, and the speed-range of the proposed machine can be extended as wide as six times of its base speed.
Dynamic susceptibility study on the skyrmion phase stability of Fe0.7Co0.3Si
Authors: Ou-Yang T. Y. , Shu G. J. , Hu C. D. , Chou F. C.
Published: March 2015

The AC susceptibilities of Fe1−xCoxSi (0.1 ≤ x ≤ 0.7) alloys were measured and compared with that of MnSi. The range of skyrmion phase in the H-T phase space was enlarged and moved to higher temperatures when approximately 1/3 of the Fe was substituted with Co. Comparing with MnSi, the skyrmion phase of Fe0.7Co0.3Si was found thermodynamically more stable under a much lower and narrower critical field near 280 ± 50 Oe. The stability range in the H-T phase space and the free energy reduction ΔE (as a function of the applied magnetic field) for both the Fe0.7Co0.3Si and MnSi were compared.
Cation ordering and effect of biaxial strain in double perovskite CsRbCaZnCl6
Authors: Pilania G. , Uberuaga B. P.
Published: March 2015

Here, we investigate the electronic structure, energetics of cation ordering, and effect of biaxial strain on double perovskite CsRbCaZnCl6 using first-principles calculations based on density functional theory. The two constituents (i.e., CsCaCl3 and RbZnCl3) forming the double perovskite exhibit a stark contrast. While CsCaCl3 is known to exist in a cubic perovskite structure and does not show any epitaxial strain induced phase transitions within an experimentally accessible range of compressive strains, RbZnCl3 is thermodynamically unstable in the perovskite phase and exhibits ultra-sensitive response at small epitaxial strains if constrained in the perovskite phase. We show that combining the two compositions in a double perovskite structure not only improves overall stability but also the strain-polarization coupling of the material. Our calculations predict a ground state with P4/nmm space group for the double perovskite, where A-site cations (i.e., Cs and Rb) are layer-ordered and B-site cations (i.e., Ca and Zn) prefer a rocksalt type ordering. The electronic structure and bandgap in this system are shown to be quite sensitive to the B-site cation ordering and is minimally affected by the ordering of A-site cations. We find that at experimentally accessible compressive strains CsRbCaZnCl6 can be phase transformed from its paraelectric ground state to an antiferroelectric state, where Zn atoms contribute predominantly to the polarization. Furthermore, both energy difference and activation barrier for a transformation between this antiferroelectric state and the corresponding ferroelectric configuration are predicted to be small. The computational approach presented here opens a new pathway towards a rational design of novel double perovskites with improved strain response and functionalities.
H-treatment impact on conductive-filament formation and stability in Ta2O5-based resistive-switching memory cells
Authors: Goux L. , Kim J. Y. , Magyari-Kope B. , Nishi Y. , Redolfi A. , Jurczak M.
Published: March 2015

In this article, we evidence the lower formation energy and improved stability of the conductive filament (CF) formed in TiN\Ta2O5\Ta resistive-switching memory cells treated in NH3 atmosphere at 400 °C. This annealing treatment results in (i) lower forming voltage, (ii) lower CF resistance, and (iii) longer retention lifetime of the oxygen-vacancy (Vo) chain constituting the CF. Atomistic insights into these processes are provided by ab initio calculations performed for hydrogen (H) species incorporated in non-stoichiometric Ta2O5 supercells: (i) Vo formation energy is reduced by the presence of H, (ii) Vo-chain CF conductivity is increased by Vo + OH complex formation, and (iii) Vo-chain retention is strengthened by the stable Vo + OH complex. As a result, efficient CF formation and excellent state stability are obtained after 15 days at 250 °C.
Domain matched epitaxial growth of (111) Ba0.5Sr0.5TiO3 thin films on (0001) Al2O3 with ZnO buffer layer
Authors: Krishnaprasad P. S. , Antony Aldrin , Rojas Fredy , Jayaraj M. K.
Published: March 2015

Epitaxial (111) Ba0.5Sr0.5TiO3 (BST) thin films have been grown by pulsed laser deposition on (0001) Al2O3 substrate with ZnO as buffer layer. The x-ray ω-2θ, Φ-scan and reciprocal space mapping indicate epitaxial nature of BST thin films. The domain matched epitaxial growth of BST thin films over ZnO buffer layer was confirmed using Fourier filtered high resolution transmission electron microscope images of the film-buffer interface. The incorporation of ZnO buffer layer effectively suppressed the lattice mismatch and promoted domain matched epitaxial growth of BST thin films. Coplanar inter digital capacitors fabricated on epitaxial (111) BST thin films show significantly improved tunable performance over polycrystalline thin films.
Directional luminescence control of InGaN/GaN heterostructures using quantum structure lattice arrays
Authors: Wang Y. L. , Chen K. Y. , Yang W. C. , Chiu S. Y. , Huang H. H. , Hung Y. C. , Cheng K. Y.
Published: March 2015

The spontaneous surface luminescence properties of InGaN/GaN quantum structure lattice (QSL) are reported. The QSL consists of a two-dimensional array of InGaN/GaN quantum boxes (QBs) arranged in a rectangular pattern of 200 nm periodicity. The measured angular dependent photoluminescence (PL) spectra show a strong dependence on the in-plane Bragg diffractions between QBs. The maximum PL intensity of the InGaN/GaN QSL array that fulfill the Bragg condition points in the normal direction of the sample surface with a narrow radiation angle of ∼ ±12°. In addition, a small side lobe is also shown at ±40°. For the QSL sample that does not fulfill the Bragg diffraction condition, the radiation pattern shows a conventional cosine distribution. The finite-difference time-domain numerical analysis confirms that the lowest order and higher order Bragg diffractions between QBs determine the main and the small side lobe of the radiation pattern measured in QSLs, respectively.
The influence of a phase shift between the top and bottom walls on the Brownian transport of self-propelled particles
Authors: Li Feng-guo , Xie Hui-zhang , Liu Xue-mei , Ai Bao-quan
Published: March 2015

Transport of noninteracting self-propelled particles is numerically investigated in a two-dimensional horizontally asymmetrical channel with nonstraight midline which can be controlled by the phase shift between the top and bottom walls. From numerical simulations, we found that self-propelled particles can be rectified by the self-propelled velocity. The direction of the average velocity is determined by the horizontally asymmetrical parameter of the channel. The average velocity is very sensitive to the phase shift and its behaviors can be manipulated by changing the phase shift. As the phase shift is increased, the average velocity decreases and its peak position moves (to right or left). Remarkably, the average velocity is zero when the phase shift is in the interval [3π/5, 4π/5]. The small phase shift may facilitate the rectification process for the large horizontal asymmetry of the channel.
Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors
Authors: Yan Hai , Zou Yi , Chakravarty Swapnajit , Yang Chun-Ju , Wang Zheng , Tang Naimei , Fan Donglei , Chen Ray T.
Published: March 2015

A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.
Geography of Knowledge Sourcing, Search Breadth and Depth Patterns, and Innovative Performance: A Firm Heterogeneity Perspective
Authors: Wang Cassandra C
Published: March 2015

The geography of knowledge sourcing has attracted much attention as firms increasingly rely on external knowledge to accelerate innovation. However, the existing literature has been silent about the way in which firms utilize external knowledge and has largely neglected firm heterogeneity in geographical knowledge sourcing. This paper established a geographical search model by combining geographical scales of knowledge sourcing with firm-level knowledge search strategies to investigate the differentiated knowledge search patterns and innovation dynamics between technological leaders and laggards with survey data from Zhejiang, one of the leading provinces in China. It is found that, while a broad search of local knowledge contributes to product innovation by technological laggards, it exerts no significant influence on technological leaders whose innovation depends more upon a nonlocal variety of knowledge sources. The findings highlight the uneven and selective knowledge flows within a cluster and question the importance of localized strong ties in innovation.
Site-Specific Dance: Revealing and Contesting the Ludic Qualities, Everyday Rhythms, and Embodied Habits of Place
Authors: Edensor Tim , Bowdler Caitlan
Published: March 2015

Focusing on three dance works and an autoethnographic account of a site-specific performance in Manchester, UK, this paper explores how contemporary site-specific dance can alter the meaning, practice, and feeling of urban spaces. Philippe Saire's Cartographies (2012) reveals the ludic and sensual potentialities of the city, Wayne Sables's Traffic (2004) foregrounds urban rhythms of place, and a piece by the Guerilla Dance Project (2010) highlights overlooked habitual practices in familiar space. To draw out these themes, we discuss a performance devised by Caitlan in Manchester's Piccadilly Gardens.
Taking the Tyke on a Bike: Mothers' and Childless Women's Space-Time Geographies in Amsterdam Compared
Authors: Eyer Amanda , Ferreira Antonio
Published: March 2015

This paper investigates the relationship between cycling and mothers' mobility in Amsterdam. Considering that mothers (still) tend to be responsible for transporting children and doing so on a bicycle may increase the difficulties of travel, the city's push for cycling may not suit mothers' mobility needs. Hence, this research aimed to uncover whether mothers' physical levels and experience of mobility by bicycle are by any means inferior to childless women's in Amsterdam. Activity-travel data, collected among thirty-seven women living and working in Amsterdam, informed the results of this research. Throughout a space-time GIS analysis, mothers barely differed from childless women in their amount of and predilection for cycling: mothers generally did not consider the transport of their children on the bicycle as an exertion or safety issue, but rather as a practical means of transport and a pleasurable moment to bond with children. However, mothers and childless women often differed in their travel schedules and purposes, implying that mothers face specific mobility challenges, which evolve as children grow older.
Using Carbon Quantum Dots as Selective Photoluminescent Probes for Protein Kinase Assay
Authors: Ding Yanjun , Kang Wenjing , Xiao Xianzhong , Wang Kangkai , Wang Nian , Zhang HuaLi , Yang Minghui , Shen Guoli
Published: March 2015

A simple and sensitive fluorescent assay is developed for the detection of protein kinase A (PKA) activity based on the selective aggregation of phosphorylated peptide–carbon quantum dots (CQDs) conjugates triggered by Zr4+ ions coordination. The peptide was conjugated onto CQDs through covalent coupling. Under optimized conditions, a linear relationship between the decreases in fluorescence intensity of peptide–CQDs and the PKA concentration in the range from 0.125 to 30 U mL–1 was observed. Moreover, the inhibition effect of H-89 on the activity of PKA was studied, and the results indicated that the proposed method showed potential applications in kinase inhibitor screening.
Synthesis and Oxidative Desulfurization of PV-Functionalized Imidazole-2-thiones: Easy Access to P-Functional Ionic Liquids
Authors: Majhi Paresh Kumar , Schnakenburg Gregor , Arduengo Anthony J. , Streubel Rainer
Published: March 2015

Selective synthesis of 4-phosphanylated imidazole-2-thiones 2d, 3a,b(b′),c(c′),d were achieved using a backbone lithiation and phosphanylation reaction protocol. The 4-phosphanylated-imidazole-2-thiones 3b(b′),c(c′) were subjected to a oxidation/phosphanylation/oxidation reaction sequence to access C4/5-bis(phosphanoyl)-substituted imidazole-2-thiones 7b,c. Oxidative desulfurization of phosphanylated imidazole-2-thiones 2d, 4a,d, and 7b,c with hydrogen peroxide afforded the first examples of room temperature imidazolium ionic liquids 8d, 9a,d, and 10b,c respectively, possessing backbone P-substituents. To study the effect of the counter anion on the physical properties, imidazolium salts with counter anions such as Cl–, BF4–, PF6–, Tf2N–, and TfO– have been prepared by exchanging the counter anion of the obtained imidazolium hydrogen sulfates 8a,d and 14b with appropriate alkali or alkaline earth metal salts. All target products were characterised by various spectroscopic and spectrometric methods and by a single-crystal X-ray structure study in the case of 5a.
Fuel dynamics and vegetation recovery after fire in a semiarid Australian shrubland
Authors: Dalgleish Sarah A. , van Etten Eddie J. B. , Stock William D. , Knuckey Chris
Published: March 2015

Understanding fuel dynamics in fire-prone ecosystems is important because fuels play a central role in shaping fire hazard and behaviour. There is ongoing debate over whether fire hazard continually increases with time since fire in shrublands of Mediterranean-type climates, and studies of the temporal changes in fuel loads can contribute to this discussion. We used a chronosequence of fire ages to investigate fuel dynamics and recovery of vegetation structure in the Acacia-dominated shrublands of interior south-west Western Australia. We collected and measured fuels from vegetation with fire ages ranging from 6 to 80+ years and then fitted linear, negative exponential, quadratic and logarithmic models to explore temporal patterns of fuel accumulation. Components of fine (<1 cm) fuel (ground, aerial live, aerial dead) and total fine fuel levels were found to accumulate rapidly in the first few years following a fire and then gradually increase for many decades thereafter. On average, total fine fuel was ~10 t ha–1 at 10 years post fire, and ~20 t ha–1 after 40–60 years. Akaike’s Information Criterion did not confidently discriminate between linear models and those that plateau at a certain fire age. However, all models showed gradual accumulation of fuel between 10 and 60 years post fire. Dead fine fuel (both litter and aerial) was virtually absent from young shrubland (<10 years) but accumulated slowly with age and comprised around 40% of total fine fuel in long-unburnt stands (>50 years). Although there is some evidence of shrub senescence in very long-unburnt vegetation (>60 years), no corresponding decline in fuel levels was detected, suggesting lag effects or inter-fire recruitment to maintain vegetation structure and fuel levels. Fuel structure and quantity varied considerably across the landscape, even within areas of the same landform and time since fire. We found that some of this variation was attributable to soil depth but suggest that other environmental factors may also cause variation in vegetation and fuel characteristics.
Structural basis for the enhancement of virulence by viral spindles and their in vivo crystallization
Authors: Chiu Elaine , Hijnen Marcel , Bunker Richard D. , Boudes Marion , Rajendran Chitra , Aizel Kaheina , Oliéric Vincent , Schulze-Briese Clemens , Mitsuhashi Wataru , Young Vivienne , Ward Vernon K. , Bergoin Max , Metcalf Peter , Coulibaly Fasséli
Published: March 2015

Significance

X-ray crystallography is a powerful approach for understanding the structure and function of biological macromolecules but is largely limited to molecules that form high-quality crystals in the laboratory. Here we present the structure of protein crystals that form naturally in virally infected insects and boost the insecticidal activity of oral pathogens. By proposing a mode of action for these virulence factors based on enzymes degrading chitin by oxidation, our findings may guide their use as synergetic additives to common bioinsecticides. They also reveal that these proteins assemble into ultra-stable crystals stabilized by a 3D network of covalent bonds, a unique strategy for achieving efficient protein crystallization in the complex environment of the cell.
Neomorphic effects of recurrent somatic mutations in
Yin Yang 1
in insulin-producing adenomas
Authors: Cromer M. Kyle , Choi Murim , Nelson-Williams Carol , Fonseca Annabelle L. , Kunstman John W. , Korah Reju M. , Overton John D. , Mane Shrikant , Kenney Barton , Malchoff Carl D. , Stalberg Peter , Akerström Göran , Westin Gunnar , Hellman Per , Carling Tobias , Björklund Peyman , Lifton Richard P.
Published: March 2015

Significance

The identical recurrent somatic heterozygous missense mutation in the DNA-binding domain of transcription factor YY1 is found in a third of insulin-secreting pancreatic tumors. This mutation alters sites involved in DNA contact and changes the DNA sequence motif that is bound, resulting in significant alteration of gene expression. Among genes showing markedly increased expression are two, an adenylyl cyclase (
ADCY1
) and a Ca
2+
channel (
CACNA2D2
), that are involved in cAMP and Ca
2+
signaling, processes known to play a role in insulin secretion. Expression of these genes in a pancreatic β-cell line causes increased insulin release. These findings provide evidence for neomorphic effects of this mutation, and demonstrate a role for altered transcription factor specificity in neoplasia.
Contrastive interlanguage analysis
Authors: Granger Sylviane
Published: March 2015

Since its introduction in 1996, Contrastive Interlanguage Analysis (CIA) has become a highly popular method in Learner Corpus Research. Its comparative design has made it possible to uncover a wide range of features distinctive of learner language and assess their degree of generalizability across learner populations. At the same time, however, the method has drawn criticism on several fronts. The purpose of this article is threefold: to provide a brief overview of CIA research, to discuss the main criticisms the method has faced in recent years and to present a revised model, CIA², which makes the central role played by variation in interlanguage studies more explicit and is generally more in line with the current state of foreign language theory and practice.
A concise synthesis of optically active solanacol, the germination stimulant for seeds of root parasitic weeds
Authors: Kumagai Hiroshi , Fujiwara Mami , Kuse Masaki , Takikawa Hirosato
Published: March 2015

Solanacol, isolated from tobacco (Nicotiana tabacum L.), is a germination stimulant for seeds of root parasitic weeds. A concise synthesis of optically active solanacol has been achieved by employing enzymatic resolution as a key step.
Influence of bench angle on upper extremity muscular activation during bench press exercise
Authors: Lauver Jakob D. , Cayot Trent E. , Scheuermann Barry W.
Published: March 2015

This study compared the muscular activation of the pectoralis major, anterior deltoid and triceps brachii during a free‐weight barbell bench press performed at 0°, 30°, 45° and –15° bench angles. Fourteen healthy resistance trained males (age 21.4 ± 0.4 years) participated in this study. One set of six repetitions for each bench press conditions at 65% one repetition maximum were performed. Surface electromyography (sEMG) was utilised to examine the muscular activation of the selected muscles during the eccentric and concentric phases. In addition, each phase was subdivided into 25% contraction durations, resulting in four separate time points for comparison between bench conditions. The sEMG of upper pectoralis displayed no difference during any of the bench conditions when examining the complete concentric contraction, however differences during 26–50% contraction duration were found for both the 30° [122.5 ± 10.1% maximal voluntary isometric contraction (MVIC)] and 45° (124 ± 9.1% MVIC) bench condition, resulting in greater sEMG compared to horizontal (98.2 ± 5.4% MVIC) and –15 (96.1 ± 5.5% MVIC). The sEMG of lower pectoralis was greater during –15° (100.4 ± 5.7% MVIC), 30° (86.6 ± 4.8% MVIC) and horizontal (100.1 ± 5.2% MVIC) bench conditions compared to the 45° (71.9 ± 4.5% MVIC) for the whole concentric contraction. The results of this study support the use of a horizontal bench to achieve muscular activation of both the upper and lower heads of the pectoralis. However, a bench incline angle of 30° or 45° resulted in greater muscular activation during certain time points, suggesting that it is important to consider how muscular activation is affected at various time points when selecting bench press exercises.
Controlled Deterministic Secure Quantum Communication Protocol Based on Three-Particle GHZ States in X-Basis*
Authors: Chang Yan , Zhang Shi-Bin , Yan Li-Li , Han Gui-Hua
Published: March 2015

A controlled deterministic secure quantum communication (CDSQC) protocol is proposed based on three-particle GHZ state in X-basis. Only X-basis and Z1Z2X3-basis (composed of Z-basis and X-basis) measurement are required, which makes the scheme more convenient than others in practical applications. By distributing a random key between both sides of the communication and performing classical XOR operation, we realize a one-time-pad scheme, therefore our protocol achieves unconditional secure. Because only user with legitimate identity string can decrypt the secret, our protocol can resist man-in-the middle attack. The three-particle GHZ state in X-basis is used as decoy photons to detect eavesdropping. The detection rate reaches 75% per qubit.
On the maximum orders of elements of finite almost simple groups and primitive permutation groups
Authors: Guest Simon , Morris Joy , Praeger Cheryl , Spiga Pablo
Published: March 2015

We determine upper bounds for the maximum order of an element of a finite almost simple group with socle

T
T

in terms of the minimum index

m
(
T
)

m(T)

of a maximal subgroup of

T
T

: for

T
T

not an alternating group we prove that, with finitely many exceptions, the maximum element order is at most

m
(
T
)

m(T)

. Moreover, apart from an explicit list of groups, the bound can be reduced to

m
(
T
)

/

4

m(T)/4

. These results are applied to determine all primitive permutation groups on a set of size

n
n

that contain permutations of order greater than or equal to

n

/

4

n/4

.
Unconventional superconductivity
Authors: Norman M. R.
Published: March 2015

This chapter provides an introduction to unconventional superconductors. It traces their development from the early days of helium-3 to the modern world of Majorana fermions. It discusses heavy fermion superconductors, cuprates, and their iron-based cousins. It emphasizes the fact that in almost all cases, an accepted microscopic theory has yet to emerge due to the difficulty of constructing a theory of superconductivity outside the Migdal–Eliashberg framework.
Atomic Bose fluids in optical lattices
Authors: Gemelke Nathan , Chin Cheng
Published: March 2015

The physics of bosonic atoms in optical lattices is described. Starting from the basic experimental tools available to create such systems, the chapter introduces a simple model (known as the Bose—Hubbard model) for such a system. A mean-field type picture is developed to determine the basic character of the superfluid and Mott-insulating phases, and the physical conditions under which each should arise. A number of experimental methods are outlined to detect the properties of the gas. The fact that two thermodynamic ground states exist at zero temperature with different types of order implies the existence of a quantum phase transition. The behavior of the gas near this transition is described using an entirely different framework—quantum criticality—formed around the concepts of scaling symmetry and the renormalization group.
Observation influence diagnostic of a data assimilation system
Authors: Cardinali C.
Published: March 2015

This chapter presents the concept of the influence matrix. Because of the cost and the possible redundancy of observations, particularly in numerical weather prediction systems, quantifying the influence of individual observations on data assimilation analysis is increasingly important. This chapter describes how the influence matrix is used to examine the influence of individual data on the analysis, the analysis change that would occur by leaving one observation out, and the effective information content (degrees of freedom for the signal) in any subset of the analysed data. A toy model is introduced to illustrate how the observation influence depends on the data assimilation covariance matrices. It is shown, in particular, that this influence strongly depends on the relative nature of the background and observation error covariance matrices.
Errors. A posteriori diagnostics
Authors: Talagrand O.
Published: March 2015

This chapter discusses three questions concerning the implementation and validation of assimilation algorithms. Objective estimation of the quality of the results of an assimilation system can be done only through comparison against independent data. Objective estimation of the statistics of the errors in the data is discussed in the context of best linear unbiased estimation, which underlies both the Kalman filter and variational assimilation. It is shown that those statistics remain totally undetermined in the absence of independent hypotheses, which cannot be objectively validated just through processing of the data. The most that can be done is to check consistency between the statistics of the innovation, as a priori implied by the specification of the data error and as a posteriori observed. Optimality of a least variance estimation procedure can be objectively evaluated against independent data using the fact that the estimation error must be statistically uncorrelated with the innovation.
Short-range error statistics in an ensemble Kalman filter
Authors: Houtekamer P.
Published: March 2015

This chapter deals with short-range error statistics in the context of the ensemble Kalman filter (EnKF). To arrive at an optimal data-assimilation system, a good description of the uncertainty in the background field is needed. Historically, different approaches, with a solid comparison against either a ground truth or observations, have been used to obtain limited descriptions. The first category includes observation system simulation experiments (OSSEs), while the second includes methods based on statistical analysis of innovations. The EnKF is a relatively new method that simulates the effect of known sources of error to arrive at a Monte Carlo estimate of flow-dependent background error statistics. It is necessary to validate the ensemble statistics–in part by comparison with results from established methods–to identify areas of improvement for the EnKF. This chapter first summarizes existing methods and then studies the properties of a research version of the Canadian global EnKF.
Structure and responsiveness
Authors: Grindrod CBE Peter
Published: March 2015

This chapter considers what dynamical models might tell about what has and has not been observed. This includes dynamics of opinions and social contacts which are time dependent and fully coupled. It considers Turing instability as a mechanism for generating patchiness in population models with both activator and inhibitory mechanisms as well as homophily. It considers how external events may drive avalanches of activity on peer-to-peer networks and also the possible exploitation of topic/interest-defined subsets of networks. It presents applications of Twitter data analysis in real time situations and to strategic decision-making in marketing.
Models of electroweak symmetry breaking
Authors: Pomarol Alex
Published: March 2015

This chapter present models of electroweak symmetry breaking arising from strongly interacting sectors, including both Higgsless models and mechanisms involving a composite Higgs. These scenarios have also been investigated in the framework of five-dimensional warped models that, according to the AdS/CFT correspondence, have a four-dimensional holographic interpretation in terms of strongly coupled field theories. We explore the implications of these models at the LHC.
AdS crunches, CFT falls, and cosmological complexity
Authors: José Luis Barbón , Eliezer Rabinovici
Published: March 2015

This chapter discusses the holographic description of crunching AdS cosmologies. Crunching FRW models with hyperbolic spatial sections are dual to semiclassical condensates in deformed de Sitter (dS) CFTs. dS-invariant condensates with a sharply defined energy scale are induced by effective negative-definite relevant or marginal operators, which may or may not destabilize the CFT. This result is obtained by explicitly constructing a “complementarity map” for this model, given by a conformal transformation of the dS CFT into a static time-frame, which reveals the crunch as an infinite potential-energy fall in finite time. Quite generically, the crunch is associated with a finite-mass black hole if the dS O(d, 1) invariance is an accidental IR symmetry, broken to U(1) × O(d) in the UV. Any such regularization cuts off the eternity of dS spacetime. Equivalently, the dimension of the Hilbert space propagating into the crunch is finite only when dS is not eternal.
Predicting protein interface residues using easily accessible on-line resources
Authors: Maheshwari Surabhi , Brylinski Michal
Published: March 2015

It has been more than a decade since the completion of the Human Genome Project that provided us with a complete list of human proteins. The next obvious task is to figure out how various parts interact with each other. On that account, we review 10 methods for protein interface prediction, which are freely available as web servers. In addition, we comparatively evaluate their performance on a common data set comprising different quality target structures. We find that using experimental structures and high-quality homology models, structure-based methods outperform those using only protein sequences, with global template-based approaches providing the best performance. For moderate-quality models, sequence-based methods often perform better than those structure-based techniques that rely on fine atomic details. We note that post-processing protocols implemented in several methods quantitatively improve the results only for experimental structures, suggesting that these procedures should be tuned up for computer-generated models. Finally, we anticipate that advanced meta-prediction protocols are likely to enhance interface residue prediction. Notwithstanding further improvements, easily accessible web servers already provide the scientific community with convenient resources for the identification of protein–protein interaction sites.
Two-group comparisons of zero-inflated intensity values: the choice of test statistic matters
Authors: Gleiss Andreas , Dakna Mohammed , Mischak Harald , Heinze Georg
Published: March 2015

Motivation: A special characteristic of data from molecular biology is the frequent occurrence of zero intensity values which can arise either by true absence of a compound or by a signal that is below a technical limit of detection.

Results: While so-called two-part tests compare mixture distributions between groups, one-part tests treat the zero-inflated distributions as left-censored. The left-inflated mixture model combines these two approaches. Both types of distributional assumptions and combinations of both are considered in a simulation study to compare power and estimation of log fold change. We discuss issues of application using an example from peptidomics.

The considered tests generally perform best in scenarios satisfying their respective distributional assumptions. In the absence of distributional assumptions, the two-part Wilcoxon test or the empirical likelihood ratio test is recommended. Assuming a log-normal subdistribution the left-inflated mixture model provides estimates for the proportions of the two considered types of zero intensities.

Availability: R code is available at http://cemsiis.meduniwien.ac.at/en/kb/science-research/software/

Contact:  georg.heinze@meduniwien.ac.at

Supplementary information:  Supplementary data are available at Bioinformatics online.
Literature, Slavery, and Colonization
Authors: Dobie Madeleine
Published: March 2015

The conquest and colonization of the Americas and the enslavement of Amerindians and Africans have inspired a large and heterogeneous body of literature. In the two centuries following Columbus’s voyage, conquistadors, missionaries, and merchants wrote accounts of contact and conquest. By the 18th century, observers in Europe were writing about the colonies and slavery in a variety of genres, including fictional, scientific, and philosophical literature. At the same time, the colonies emerged as sites of literary production by writers of various backgrounds, including a small number of Amerindians and a larger contingent of “creole” writers of European descent. By the end of the 18th century, several former slaves had written autobiographical narratives recounting their experience of servitude. The African diaspora and slavery also created conditions for the interpretation of skin color as a marker of human diversity, giving rise to theories of race, including a significant corpus of scientific writing and reflections on the social, political, and cultural identity of Afro-descendants in the Americas. The 19th century was marked by several interconnected transitions. Beginning with the United States and Haiti, colonies began to gain their independence, European economic and strategic interests shifted toward Africa and Asia, slavery was abolished, and new imperial ideologies such as the “civilizing mission” gained currency. Literary culture evolved in parallel with these changes. Notably, slavery became an object of sustained critique by writers from around the Atlantic rim. Scholarship on the literary imprint of colonization and slavery in the Atlantic world has predominantly been organized by language, though there are also comparative studies that cross linguistic boundaries. Some studies are anchored within the framework of a particular imperial history, e.g., the British or French, while others advocate for transnational or regional categories such as “the Americas,” “the Atlantic world,” or “the black Atlantic,” arguing that these better reflect the circulation of people, ideas, and texts. One challenge of establishing a critical bibliography on the literature associated with colonialism and slavery is that literature is a fluid category and, as a result, literary scholarship overlaps significantly with cultural history. In addition to studies of narrative fiction and poetry, this bibliography includes scholarship on autobiographical, philosophical, economic, and scientific writing. Research on literature and colonization has expanded significantly since the advent of postcolonial studies in the 1980s, hence the heavy representation of research published since this watershed. Postcolonial theory and studies of postcolonial literature are, however, not included, with the exception of those that emphasize the memory of colonization and slavery.