bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical predominance of Dirichlet condition for the one-dimensional Coulomb potential
Authors: de Oliveira César R. , Verri Alessandra A.
Published: May 2012

We restrict a quantum particle under a Coulombian potential (i.e., the Schrödinger operator with inverse of the distance potential) to three-dimensional tubes along the x axis and diameter ɛ, and study the confining limit ɛ → 0. In the repulsive case we prove a strong resolvent convergence to a one-dimensional limit operator, which presents Dirichlet boundary condition at the origin. Due to the possibility of the falling of the particle in the center of force, in the attractive case we need to regularize the potential and also prove a norm resolvent convergence to the Dirichlet operator at the origin. Thus, it is argued that, among the infinitely many self-adjoint realizations of the corresponding problem in one dimension, the Dirichlet boundary condition at the origin is the reasonable one-dimensional limit.
Implementation of moiré-schlieren deflectometry on a small scale fast capillary plasma discharge
Authors: Valenzuela J. C. , Wyndham E. S. , Chuaqui H. , Cortes D. S. , Favre M. , Bhuyan H.
Published: May 2012

We present the results of an implementation of a refractive diagnostic to study fast dynamics in capillary discharges. It consists of a moiré-schlieren deflectometry technique that provides a quantitative analysis of the refractive index gradients. The technique is composed of an angular deflection mapping system (moiré deflectometry) and a spatial Fourier filter (schlieren). Temporal resolution of 12 ps, 50 μm of spatial resolution and minimum detectable gradient of (∇ne)min=6×1018cm-4 were obtained. With these parameters, a large aspect ratio capillary discharge of 15 ns half period current was studied; the diagnostic was implemented axially along the alumina tube of 1.6 mm inner diameter and 21 mm length. The detectable electron density for these conditions was 1×1017cm-3. From the interpretation of the fringe displacement, we are able to measure the velocity of the radial compression wave and the compression ratio due to the Lorentz force. On axis, electron densities of the order of 5×1017cm-3 were obtained at the time of maximum soft x-ray emission.
One-particle correlation function in evanescent wave dynamic light scattering
Authors: Lisicki Maciej , Cichocki Bogdan , Dhont Jan K. G. , Lang Peter R.
Published: May 2012

In order to interpret measured intensity autocorrelation functions obtained in evanescent wave scattering, their initial decay rates have been analyzed recently [P. Holmqvist, J. K. G. Dhont, and P. R. Lang, Phys. Rev. E 74, 021402 (2006)10.1103/PhysRevE.74.021402; B. Cichocki, E. Wajnryb, J. Blawzdziewicz, J. K. G. Dhont, and P. R. Lang, J. Chem. Phys. 132, 074704 (2010)10.1063/1.3305328; J. W. Swan and J. F. Brady, J. Chem. Phys. 135, 014701 (2011)]10.1063/1.3604530. A theoretical analysis of the longer time dependence of evanescent wave autocorrelation functions, beyond the initial decay, is still lacking. In this paper we present such an analysis for very dilute suspensions of spherical colloids. We present simulation results, a comparison to cumulant expansions, and experiments. An efficient simulation method is developed which takes advantage of the particular mathematical structure of the time-evolution equation of the probability density function of the position coordinate of the colloidal sphere. The computer simulation results are compared with analytic, first and second order cumulant expansions. The only available analytical result for the full time dependence of evanescent wave autocorrelation functions [K. H. Lan, N. Ostrowsky, and D. Sornette, Phys. Rev. Lett. 57, 17 (1986)]10.1103/PhysRevLett.57.17, that neglects hydrodynamic interactions between the colloidal spheres and the wall, is shown to be quite inaccurate. Experimental results are presented and compared to the simulations and cumulant expansions.
Screen printed ZnO ultraviolet photoconductive sensor on pencil drawn circuitry over paper
Authors: ul Hasan Kamran , Nur Omer , Willander Magnus
Published: May 2012

Many applications require a low-cost and large-scale mode of flexible electronics with reasonably high photoresponse that can be detected without high precision measurement systems. We demonstrate a very easy to fabricate ZnO UV sensor, made on common pencil drawn circuit over a paper. ZnO nanocrystals were extracted in a high throughput via a simple and green route. This sensor is well capable of detecting UV light and demonstrates features comparable to those of made with complex and expensive techniques.
The conformational flexibility of nucleic acid bases paired in gas phase: A Car-Parrinello molecular dynamics study
Authors: Xiao Shiyan , Liang Haojun
Published: May 2012

The flexibilities of pyrimidine and imidazole rings in the paired nucleobases are investigated using Car-Parrinello molecular dynamics simulation in gas phase. The pairing influence on the stiffness of rings is analyzed based on the molecular structure of the nucleobases and constraints caused by pairing. We prove that the flexibilities of pyrimidine rings in isolated state have subtle correlation with the degree of aromaticity of the rings. The pairings in nucleic base pairs cause the rings to be more rigid for G, T, and U but more flexible for A and the same for C.
Recycling failed bulk YBCO superconductors using the NdBCO/YBCO/MgO film-seeded top-seeded melt growth method
Authors: Xu H. H. , Cheng L. , Yan S. B. , Yu D. J. , Guo L. S. , Yao X.
Published: May 2012

REBa2Cu3Oy (RE123 or REBCO, RE = rare earth elements) bulk high-temperature superconductors have a potential perspective for large-scale engineering applications. However, the cost of REBCO bulk production is rather high, considering high failure rates, expensive RE materials, and Pt or Ag addition. Using the cold-seeding in the top-seeded melt growth, a simple and feasible process, we succeeded in recycling the failed REBCO (RE = Y) bulks. The distinctive feature of this recycling process is the use of YBCO-buffered NdBCO films as seeds, which have high thermal stability and can endure a maximum processing temperature (Tmax) up to 1120 °C to enable full decomposition of solid REBCO. Three typical microstructures were recognized in the failed samples attributed to the inherent differences in the non-optimized growth heating profiles. Preferential recycling procedures were chosen according to the difficulty of the failed-samples decomposition, which has a certain connection with the microstructures of the failed bulks. Finally, after oxygenation, the recycled bulks demonstrate good superconducting properties.
Infrared limit in external field scattering
Authors: Herdegen Andrzej
Published: May 2012

Scattering of electrons/positrons by external classical electromagnetic wave packet is considered in infrared limit. In this limit, the scattering operator exists and produces physical effects, although the scattering cross-section is trivial.
Lattice mismatch and crystallographic tilt induced by high-dose ion-implantation into 4H-SiC
Authors: Sasaki S. , Suda J. , Kimoto T.
Published: May 2012

Lattice parameters of high-dose ion-implanted 4H-SiC were investigated with reciprocal space mapping (RSM). N, P, Al, or (C+Si) ions were implanted into lightly doped epilayers to form a (330–520) nm-deep box profile with concentrations of 1019-1020atoms/cm3. After activation annealing at 1800 °C, RSM measurements were conducted. The RSM images for (0008) reflection revealed that high-dose ion implantation causes c-lattice expansion in implanted layers, irrespective of ion species. In addition, crystallographic tilt was observed after high-dose ion implantation. The tilt direction is the same for all the samples investigated; the c-axis of the implanted layers is inclined toward the ascending direction of the off-cut. The c-lattice mismatch and the tilt angle increased as the implantation dose increases, indicating that the implantation damage is responsible for the lattice parameter change. From these results and transmission electron microscopy observation, the authors conclude that the c-lattice mismatch and the crystallographic tilt are mainly caused by secondary defects formed after the ion-implantation and activation-annealing process.
Charge recombination in disordered neat polymer films under imbalanced excitation conditions studied using the recombination time of flight technique
Authors: Ravia Israel , Tessler Nir
Published: May 2012

It has recently been suggested that the charge recombination rate in amorphous polymers could be affected by the energy distribution of electrons and holes as well as that of the resulting excitons. To test this hypothesis, we developed a new method for measuring charge recombination under highly imbalanced conditions. We find that if the electron density is higher than that of the holes, increasing the electron density further results in reduction of the recombination coefficient. We attribute this to the very different energy distribution between low and high carrier densities, which is not accounted for in the Langevin recombination model.
Grafting polymer coatings onto the surfaces of carbon nanotube forests and yarns via a photon irradiation process
Authors: Deng Fei , Rujisamphan N. , Liu Chang , Maezono Yoshinari , Hawkins Stephen C. , Huynh Chi P. , Ismat Shah S. , Ni Chaoying
Published: May 2012

Surface activation of carbon nanotubes (CNTs) as forests and yarns, depolytmerization of candidate polymers, and uniform deposition and re-polymerization onto the activated CNTs are simultaneously achieved by exposing CNTs and polymer targets to light with a narrow wavelength distribution from a vacuum ultraviolet lamp. Both polystyrene and poly (methyl methacrylate) are deposited onto the surface of CNTs in the CNT-forest and yarn in a N2 environment for 30 min during which the polymer uniformly coats the carbon nanotubes. X-ray photoelectron spectroscopy data reveal that covalent bonding occurs at the CNT-polymer interface.
Mirrors for slow neutrons from holographic nanoparticle-polymer free-standing film-gratings
Authors: Klepp J. , Pruner C. , Tomita Y. , Mitsube K. , Geltenbort P. , Fally M.
Published: May 2012

We report on tests of holographically arranged grating-structures in nanoparticle-polymer composites in the form of 100 μm thin free-standing films, i.e., without sample containers or covers that could cause unwanted absorption/incoherent scattering of very-cold neutrons. Despite their large diameter of 2 cm, the flexible materials are of high optical quality and yield mirror-like reflectivity of about 90% for neutrons of 4.1 nm wavelength.
Effects of tip-substrate gap, deposition temperature, holding time, and pull-off velocity on dip-pen lithography investigated using molecular dynamics simulation
Authors: Wu Cheng-Da , Fang Te-Hua , Lin Jen-Fin
Published: May 2012

The process parameters in the dip-pen nanolithography process, including tip-substrate gap, deposition temperature, holding time, and pull-off velocity are evaluated in terms of the mechanism of molecular transference, alkanethiol meniscus characteristic, surface adsorbed energy, and pattern formation using molecular dynamics simulations. The simulation results clearly show that the optimum deposition occurs at a smaller tip-substrate gap, a slower pull-off velocity, a higher temperature, and a longer holding time. The pattern area increases with decreasing tip-substrate gap and increasing deposition temperature and holding time. With an increase in deposition temperature, the molecular transfer ability significantly increases. Pattern height is a function of meniscus length. When the pull-off velocity is decreased, the pattern height increases. The height of the neck in meniscus decreases and the neck width increases with holding time. Meniscus size increases with increasing deposition temperature and holding time.
Compact inductive energy storage pulse power system
Authors: K Senthil , Mitra S. , Roy Amitava , Sharma Archana , Chakravarthy D. P.
Published: May 2012

An inductive energy storage pulse power system is being developed in BARC, India. Simple, compact, and robust opening switches, capable of generating hundreds of kV, are key elements in the development of inductive energy storage pulsed power sources. It employs an inductive energy storage and opening switch power conditioning techniques with high energy density capacitors as the primary energy store. The energy stored in the capacitor bank is transferred to an air cored storage inductor in 5.5 μs through wire fuses. By optimizing the exploding wire parameters, a compact, robust, high voltage pulse power system, capable of generating reproducibly 240 kV, is developed. This paper presents the full details of the system along with the experimental data.
Defect-free localized modes and coupled-resonator acoustic waveguides constructed in two-dimensional phononic quasicrystals
Authors: Zhang Mingda , Zhong Wei , Zhang Xiangdong
Published: May 2012

The localization of acoustic waves in defect-free two-dimensional quasiperiodic phononic crystals has been investigated by using an exact multiple-scattering method. Different types of localized states have been found in eightfold, tenfold, and twelvefold two-dimensional phononic quasicrystals without introducing any defect. The defect-free coupled-resonator acoustic waveguides, based on these localized modes, have been designed, and the resonant transmission properties of acoustic waves in the waveguides have been demonstrated by numerical simulations. It is anticipated that our findings can be potentially applied to phononic devices.
Non-equilibrium quantum well populations and active region inhomogeneity in polar and nonpolar III-nitride light emitters
Authors: Kisin Mikhail V. , Chuang Chih-Li , El-Ghoroury Hussein S.
Published: May 2012

Strong disparity of electron and hole transport in III-nitride materials is commonly accepted as a main reason for inhomogeneous carrier injection in multiple-quantum well (MQW) active regions of light emitters operating in visible spectral range. In this work, we show that two more factors, specifically (i) excessive depth of III-nitride QWs and (ii) strongly non-equilibrium character of electron and hole populations in optically active QW, are responsible for the active region inhomogeneity in GaN-based light emitters. Modeling shows that electron and hole populations of deep III-nitride QWs are highly imbalanced and substantially deviate from thermodynamic equilibrium with corresponding mobile carrier subsystems in the device active region. In turn, large residual QW charges provide strong impact on the active region electrical uniformity and QW injection conditions. We demonstrate that, as a result of non-equilibrium effects in QW population, even nonpolar III-nitride light emitters with deep QWs suffer from inhomogeneous carrier injection, large QW residual charges, and overall electrical non-uniformity of MQW active regions.
CO adsorption and desorption on size-selected Pdn/TiO2(110) model catalysts: Size dependence of binding sites and energies, and support-mediated adsorption
Authors: Kaden William E. , Kunkel William A. , Roberts F. Sloan , Kane Matthew , Anderson Scott L.
Published: May 2012

The nature of CO adsorption on Pdn/TiO2(110) (n = 1, 2, 7, 20) has been examined using temperature-programmed desorption (TPD), temperature-dependent helium ion scattering (TD-ISS), and X-ray photoelectron spectroscopy (XPS). All samples contain the same number of Pd atoms (0.10 ML-equivalent) deposited as different size clusters. The TPD and TD-ISS show that CO binds in two types of sites associated with the Pd clusters. The most stable sites are on top of the Pd clusters (“on-top” sites), however, there are also less stable sites, in which CO is bound in association with, but not on top of the Pd (“peripheral” sites). For saturation CO coverage over a fixed atomic concentration of Pd (present in the form of Pdn clusters of varying size), the population of CO in peripheral sites decreases with increasing cluster size, while the on-top site population is size-independent. This is consistent with what geometric considerations would predict for the density of the two types of sites, provided the clusters adsorb predominantly as 2D islands, which ISS results suggest to be the case. The XPS analysis indicates that CO-Pd binding is dominated by π-backbonding to the Pdn clusters. The results also show evidence for efficient support-mediated adsorption (reverse-spillover) of CO initially impinging on TiO2 to binding sites associated with the Pd clusters.
Optimization of an electrokinetic mixer for microfluidic applications
Authors: Bockelmann Hendryk , Heuveline Vincent , Barz Dominik P. J.
Published: May 2012

This work is concerned with the investigation of the concentration fields in an electrokinetic micromixer and its optimization in order to achieve high mixing rates. The mixing concept is based on the combination of an alternating electrical excitation applied to a pressure-driven base flow in a meandering microchannel geometry. The electrical excitation induces a secondary electrokinetic velocity component, which results in a complex flow field within the meander bends. A mathematical model describing the physicochemical phenomena present within the micromixer is implemented in an in-house finite-element-method code. We first perform simulations comparable to experiments concerned with the investigation of the flow field in the bends. The comparison of the complex flow topology found in simulation and experiment reveals excellent agreement. Hence, the validated model and numerical schemes are employed for a numerical optimization of the micromixer performance. In detail, we optimize the secondary electrokinetic flow by finding the best electrical excitation parameters, i.e., frequency and amplitude, for a given waveform. Two optimized electrical excitations featuring a discrete and a continuous waveform are discussed with respect to characteristic time scales of our mixing problem. The results demonstrate that the micromixer is able to achieve high mixing degrees very rapidly.
Schottky diode with excellent performance for large integration density of crossbar resistive memory
Authors: Hwan Kim Gun , Ho Lee Jong , Hwan Han Jeong , Ji Song Seul , Yeong Seok Jun , Ho Yoon Jung , Jean Yoon Kyung , Hwan Lee Min , Joo Park Tae , Seong Hwang Cheol
Published: May 2012

A Schottky diode (SD) with Au/Pt/TiO2/Ti/Pt stacked structure were fabricated for its application to crossbar type resistive switching (RS) memory. The SDs showed a highly promising rectification ratio (∼2.4 × 106 @ ±2 V) between forward and reverse state currents and a high forward current density (∼3 × 105 A/cm2 @ 2 V), which is useful for highly integrated crossbar RS memory. The SD has local forward current conduction paths, which provides extremely scaled devices with an advantage. The minimization of interconnection line resistance is also important to provide sufficient current to achieve stable operation of RS memory.
Atomistic study on the strength of symmetric tilt grain boundaries in graphene
Authors: Cao Ajing , Yuan Yutang
Published: May 2012

Molecular dynamics (MD) simulations were employed to study the mechanical response of various bicrystal graphene consisting of symmetric tilt boundary subject to uniaxial tensile loading at room temperature. We found that the strength of zigzag-oriented graphene increases slightly with mis-orientation angle, while the strength of armchair-oriented graphene deceases slightly with mis-orientation angle. Given that the difference in strength is small, one might conclude that the dependence of strength of graphene sheet containing grain boundaries upon tilt mis-orientation angle is rather weak. The origin for such weak dependence is believed to be that these grain boundaries all consisting of pentagon-heptagon pairs do not resemble nano-cracks, which result in rather heterogeneous stress field around the crack tip and therefore stress gradient plays an important role.
Full-field deformation of magnetorheological elastomer under uniform magnetic field
Authors: Gong Xinglong , Liao Guojiang , Xuan Shouhu
Published: May 2012

A digital holographic interferometry was applied to analyze the morphology transformation of the magnetorheological elastomer, and both the contraction and stretch deformation were observed under applying an external magnetic field on the sample. Both isolated particles and grouped particles were observed in the magnetorheological elastomer sample, and these two kinds of particles resulted in the concave-convex deformation of the sample. The deformation of magnetorheological elastomer was calculated by using a 2D finite element model, and the results agreed well with the experimental analysis.
Direct magnetic resonance detection of myelin and prospects for quantitative imaging of myelin density
Authors: Wilhelm Michael J. , Ong Henry H. , Wehrli Suzanne L. , Li Cheng , Tsai Ping-Huei , Hackney David B. , Wehrli Felix W.
Published: May 2012

Magnetic resonance imaging has previously demonstrated its potential for indirectly mapping myelin density, either by relaxometric detection of myelin water or magnetization transfer. Here, we investigated whether myelin can be detected and possibly quantified directly. We identified the spectrum of myelin in the spinal cord in situ as well as in myelin lipids extracted via a sucrose gradient method, and investigated its spectral properties. High-resolution solution NMR spectroscopy showed the extract composition to be in agreement with myelin’s known chemical make-up. The 400-MHz
1
H spectrum of the myelin extract, at 20 °C (room temperature) and 37 °C, consists of a narrow water resonance superimposed on a broad envelope shifted ∼3.5 ppm upfield, suggestive of long-chain methylene protons. Superimposed on this signal are narrow components resulting from functional groups matching the chemical shifts of the constituents making up myelin lipids. The spectrum could be modeled as a sum of super-Lorentzians with a T
2
* distribution covering a wide range of values (0.008–26 ms). Overall, there was a high degree of similarity between the spectral properties of extracted myelin lipids and those found in neural tissue. The normalized difference spectrum had the hallmarks of membrane proteins, not present in the myelin extract. Using 3D radially ramp-sampled proton MRI, with a combination of adiabatic inversion and echo subtraction, the feasibility of direct myelin imaging in situ is demonstrated. Last, the integrated signal from myelin suspensions is shown, both spectroscopically and by imaging, to scale with concentration, suggesting the potential for quantitative determination of myelin density.
Wave-particle dualism and complementarity unraveled by a different mode
Authors: Menzel Ralf , Puhlmann Dirk , Heuer Axel , Schleich Wolfgang P.
Published: May 2012

The precise knowledge of one of two complementary experimental outcomes prevents us from obtaining complete information about the other one. This formulation of Niels Bohr’s principle of complementarity when applied to the paradigm of wave-particle dualism—that is, to Young’s double-slit experiment—implies that the information about the slit through which a quantum particle has passed erases interference. In the present paper we report a double-slit experiment using two photons created by spontaneous parametric down-conversion where we observe interference in the signal photon despite the fact that we have located it in one of the slits due to its entanglement with the idler photon. This surprising aspect of complementarity comes to light by our special choice of the TEM
01
pump mode. According to quantum field theory the signal photon is then in a coherent superposition of two distinct wave vectors giving rise to interference fringes analogous to two mechanical slits.
Characterizing Seasonal Habitat Use and Diel Vertical Activity of Lake Whitefish in Clear Lake, Maine, as Determined with Acoustic Telemetry
Authors: Gorsky Dimitry , Zydlewski Joseph , Basley David
Published: May 2012

Seasonal and daily vertical activity of lake whitefishCoregonus clupeaformiswas studied in Clear Lake, Maine (253 ha), using acoustic telemetry from November 2004 to June 2009. Twenty adult lake whitefish were tagged with acoustic tags that had either a depth sensor or both depth and temperature sensors to assess vertical habitat use at a seasonal and daily resolution. Vertical habitat selection varied seasonally and was strongly influenced by temperature. Between December and April, when the lake was covered with ice, surface temperature was below 2°C and tagged individuals occupied deep areas of the lake (∼15 m). After ice‐out, fish ascended into shallow waters (∼5 m), responding to increased water temperature and possibly to greater foraging opportunity. When surface water temperatures exceeded 20°C, fish descended below the developing thermocline (∼9 m), where they remained until surface temperatures fell below 20°C; fish then ascended into shallower depths, presumably for feeding and spawning. Through the winter, fish remained in thermal habitats that were warmer than the surface temperatures; in the summer, they selected depths with thermal habitats below 15°C. Though the amplitude varied greatly across seasons, lake whitefish displayed a strong diurnal pattern of activity as measured by vertical velocities. Fish were twofold more active during spring, summer, and fall than during winter. Lake whitefish exhibited diel vertical migrations, rising in the water column during nighttime and occupying deeper waters during the day. This pattern was more pronounced in the spring and fall and far less prominent during winter and summer. The strong linkage between temperature and habitat use may limit the current range of lake whitefish and may be directly impacted by climatic change.
Energy Density of Bloaters in the Upper Great Lakes
Authors: Pothoven Steven A. , Bunnell David B. , Madenjian Charles P. , Gorman Owen T. , Roseman Edward F.
Published: May 2012

We evaluated the energy density of bloaters Coregonus hoyi as a function of fish size across Lakes Michigan, Huron, and Superior in 2008–2009 and assessed how differences in energy density are related to factors such as biomass density of bloaters and availability of prey. Additional objectives were to compare energy density between sexes and to compare energy densities of bloaters in Lake Michigan between two time periods (1998–2001 and 2008–2009). For the cross‐lake comparisons in 2008, energy density increased with fish total length (TL) only in Lake Michigan. Mean energy density adjusted for fish size was 8% higher in bloaters from Lake Superior than in bloaters from Lake Huron. Relative to fish in these two lakes, small (<125 mm TL) bloaters from Lake Michigan had lower energy density, whereas large (>175 mm TL) bloaters had higher energy density. In 2009, energy density increased with bloater size, and mean energy density adjusted for fish size was about 9% higher in Lake Michigan than in Lake Huron (Lake Superior was not sampled during 2009). Energy density of bloaters in Lake Huron was generally the lowest among lakes, reflecting the relatively low densities of opossum shrimp Mysis diluviana and the relatively high biomass of bloaters reported for that lake. Other factors, such as energy content of prey, growing season, or ontogenetic differences in energy use strategies, may also influence cross‐lake variation in energy density. Mean energy density adjusted for length was 7% higher for female bloaters than for male bloaters in Lakes Michigan and Huron. In Lake Superior, energy density did not differ between males and females. Finally, energy density of bloaters in Lake Michigan was similar between the periods 2008–2009 and 1998–2001, possibly due to a low population abundance of bloaters, which could offset food availability changes linked to the loss of prey such as the amphipods Diporeia spp.
Statistical models as cognitive models of individual differences in reasoning
Authors: Fugard Andrew J.B. , Stenning Keith
Published: May 2012

There are individual differences in reasoning which go beyond dimensions of ability. Valid models of cognition must take these differences into account, otherwise they characterise group mean phenomena which explain nobody. The gap is closing between formal cognitive models, which are designed from the ground up to explain cognitive phenomena, and statistical models, which traditionally concern the more modest task of modelling relationships in data. This paper critically reviews three illustrative statistical models of individual differences in reasoning which embed some notion of cognitive process. Although the models are each developed in different frameworks, it is shown that they are more similar than would first appear. The cognitive meaning of elements in the example models is explored and some sketches are developed for future directions of research.
Legal idioms: a framework for evidential reasoning
Authors: Lagnado David A. , Fenton Norman , Neil Martin
Published: May 2012

How do people make legal judgments based on complex bodies of interrelated evidence? This paper outlines a novel framework for evidential reasoning using causal idioms. These idioms are based on the qualitative graphical component of Bayesian networks, and are tailored to the legal context. They can be combined and reused to model complex bodies of legal evidence. This approach is applied to witness and alibi testimony, and is illustrated with a real legal case. We show how the framework captures critical aspects of witness reliability, and the potential interrelations between witness reliabilities and other hypotheses and evidence. We report a brief empirical study on the interpretation of alibi evidence, and show that people's intuitive inferences fit well with the qualitative aspects of the idiom-based framework.
A tunable hybrid metamaterial absorber based on vanadium oxide films
Authors: Wen Qi-Ye , Zhang Huai-Wu , Yang Qing-Hui , Chen Zhi , Long Yang , Jing Yu-Lan , Lin Yuan , Zhang Pei-Xin
Published: May 2012

A tunable hybrid metamaterial absorber (MA) in the microwave band was designed, fabricated and characterized. The hybrid MA was realized by incorporating a VO2 film into the conventional resonant MA. By thermally triggering the insulator–metal phase transition of the VO2 film, the impedance match condition was broken and a deep amplitude modulation of about 63.3% to the electromagnetic wave absorption was achieved. A moderate blue-shift of the resonance frequency was observed which is promising for practical applications. This VO2-based MA exhibits many advantages such as strong tunability, frequency agility, simple fabrication and ease of scaling to the terahertz band.
Comparison of electromagnetic interference shielding properties between single-wall carbon nanotube and graphene sheet/polyaniline composites
Authors: Yuan Bingqing , Yu Liming , Sheng Leimei , An Kang , Zhao Xinluo
Published: May 2012

Single-wall carbon nanotube/polyaniline (SWCNT/PANI) and graphene sheet/polyaniline (GS/PANI) composites were prepared by a simple alcohol-assisted dispersion and pressing process. The SWCNTs and GSs were synthesized by the dc arc-discharge method. The dc electrical conductivity and the electromagnetic interference (EMI) shielding effectiveness (SE) of these two kinds of composites were measured. The experimental results reveal that the conductivity and the EMI SE of the GS/PANI composite are better than that of the SWCNT/PANI composite, and the absorption proportion of the SWCNT/PANI composite is higher than that of the GS/PANI composite. The EMI shielding results (2–18 GHz) also show that both composites present an absorption-dominant mechanism and present a wide application prospect in the field of EMI shielding and microwave absorption.
Effect of cadmium sulfide nanorod content on Freedericksz threshold voltage, splay and bend elastic constants in liquid-crystal nanocomposites
Authors: Nayek Prasenjit , Karan Santanu , Kundu Sudarshan , Lee Seung Hee , Gupta Sudeshna Das , Roy Soumen Kumar , Roy Subir Kumar
Published: May 2012

This report describes how doping liquid crystals (LC) with rod-like hexagonal semiconductor nanoprisms alters the dielectric and elastic properties of the composites as compared with a pristine nematic liquid crystal (NLC). Cadmium sulfide nanorods were synthesized via the solvothermal process and blended with a NLC. Nanorods were highly miscible with NLC and produced a topological defect-free texture up to a certain limit. A good dark state was achieved during the homeotropic configuration of the cell within that limit. Appreciable changes in splay and bend elastic constants of the LCs were observed after blending with nanorods. Long-range order was established in the hybrid system, and consequently the anisotropy was increased. The threshold voltage decreased dramatically by ∼31%. Dielectric study revealed a high-frequency mode, which might be due to anchoring of the LC with nanorods.
Application of survival analysis methodology to the quantitative analysis of LC-MS proteomics data
Authors: Tekwe Carmen D. , Carroll Raymond J. , Dabney Alan R.
Published: May 2012

Motivation: Protein abundance in quantitative proteomics is often based on observed spectral features derived from liquid chromatography mass spectrometry (LC-MS) or LC-MS/MS experiments. Peak intensities are largely non–normal in distribution. Furthermore, LC-MS-based proteomics data frequently have large proportions of missing peak intensities due to censoring mechanisms on low-abundance spectral features. Recognizing that the observed peak intensities detected with the LC-MS method are all positive, skewed and often left-censored, we propose using survival methodology to carry out differential expression analysis of proteins. Various standard statistical techniques including non-parametric tests such as the Kolmogorov–Smirnov and Wilcoxon–Mann–Whitney rank sum tests, and the parametric survival model and accelerated failure time-model with log-normal, log-logistic and Weibull distributions were used to detect any differentially expressed proteins. The statistical operating characteristics of each method are explored using both real and simulated datasets.

Results: Survival methods generally have greater statistical power than standard differential expression methods when the proportion of missing protein level data is 5% or more. In particular, the AFT models we consider consistently achieve greater statistical power than standard testing procedures, with the discrepancy widening with increasing missingness in the proportions.

Availability: The testing procedures discussed in this article can all be performed using readily available software such as R. The R codes are provided as supplemental materials.

Contact:  ctekwe@stat.tamu.edu
Multi-scale computational modeling of developmental biology
Authors: Setty Yaki
Published: May 2012

Motivation: Normal development of multicellular organisms is regulated by a highly complex process in which a set of precursor cells proliferate, differentiate and move, forming over time a functioning tissue. To handle their complexity, developmental systems can be studied over distinct scales. The dynamics of each scale is determined by the collective activity of entities at the scale below it.

Results: I describe a multi-scale computational approach for modeling developmental systems and detail the methodology through a synthetic example of a developmental system that retains key features of real developmental systems. I discuss the simulation of the system as it emerges from cross-scale and intra-scale interactions and describe how an in silico study can be carried out by modifying these interactions in a way that mimics in vivo experiments. I highlight biological features of the results through a comparison with findings in Caenorhabditis elegans germline development and finally discuss about the applications of the approach in real developmental systems and propose future extensions.

Availability and implementation: The source code of the model of the synthetic developmental system can be found in www.wisdom.weizmann.ac.il/~yaki/MultiScaleModel.

Contact:  yaki.setty@gmail.com

Supplementary information:  Supplementary data are available at Bioinformatics online.
RAxML-Light: a tool for computing terabyte phylogenies
Authors: Stamatakis A. , Aberer A.J. , Goll C. , Smith S.A. , Berger S.A. , Izquierdo-Carrasco F.
Published: May 2012

Motivation: Due to advances in molecular sequencing and the increasingly rapid collection of molecular data, the field of phyloinformatics is transforming into a computational science. Therefore, new tools are required that can be deployed in supercomputing environments and that scale to hundreds or thousands of cores.

Results: We describe RAxML-Light, a tool for large-scale phylogenetic inference on supercomputers under maximum likelihood. It implements a light-weight checkpointing mechanism, deploys 128-bit (SSE3) and 256-bit (AVX) vector intrinsics, offers two orthogonal memory saving techniques and provides a fine-grain production-level message passing interface parallelization of the likelihood function. To demonstrate scalability and robustness of the code, we inferred a phylogeny on a simulated DNA alignment (1481 taxa, 20 000 000 bp) using 672 cores. This dataset requires one terabyte of RAM to compute the likelihood score on a single tree.

Code Availability:  https://github.com/stamatak/RAxML-Light-1.0.5

Data Availability:  http://www.exelixis-lab.org/onLineMaterial.tar.bz2

Contact:  alexandros.stamatakis@h-its.org

Supplementary Information:  Supplementary data are available at Bioinformatics online.
Solar flares and energetic particles
Authors: Vilmer Nicole
Published: May 2012

Solar flares are now observed at all wavelengths from
γ
-rays to decametre radio waves. They are commonly associated with efficient production of energetic particles at all energies. These particles play a major role in the active Sun because they contain a large amount of the energy released during flares. Energetic electrons and ions interact with the solar atmosphere and produce high-energy X-rays and
γ
-rays. Energetic particles can also escape to the corona and interplanetary medium, produce radio emissions (electrons) and may eventually reach the Earth's orbit. I shall review here the available information on energetic particles provided by X-ray/γ-ray observations, with particular emphasis on the results obtained recently by the mission Reuven Ramaty High-Energy Solar Spectroscopic Imager. I shall also illustrate how radio observations contribute to our understanding of the electron acceleration sites and to our knowledge on the origin and propagation of energetic particles in the interplanetary medium. I shall finally briefly review some recent progress in the theories of particle acceleration in solar flares and comment on the still challenging issue of connecting particle acceleration processes to the topology of the complex magnetic structures present in the corona.
A contemporary view of coronal heating
Authors: Parnell Clare E. , De Moortel Ineke
Published: May 2012

Determining the heating mechanism (or mechanisms) that causes the outer atmosphere of the Sun, and many other stars, to reach temperatures orders of magnitude higher than their surface temperatures has long been a key problem. For decades, the problem has been known as the coronal heating problem, but it is now clear that ‘coronal heating’ cannot be treated or explained in isolation and that the heating of the whole solar atmosphere must be studied as a highly coupled system. The magnetic field of the star is known to play a key role, but, despite significant advancements in solar telescopes, computing power and much greater understanding of theoretical mechanisms, the question of which mechanism or mechanisms are the dominant supplier of energy to the chromosphere and corona is still open. Following substantial recent progress, we consider the most likely contenders and discuss the key factors that have made, and still make, determining the actual (coronal) heating mechanism (or mechanisms) so difficult.
Social complexity as a proximate and ultimate factor in communicative complexity
Authors: Freeberg Todd M. , Dunbar Robin I. M. , Ord Terry J.
Published: May 2012

The ‘social complexity hypothesis’ for communication posits that groups with complex social systems require more complex communicative systems to regulate interactions and relations among group members. Complex social systems, compared with simple social systems, are those in which individuals frequently interact in many different contexts with many different individuals, and often repeatedly interact with many of the same individuals in networks over time. Complex communicative systems, compared with simple communicative systems, are those that contain a large number of structurally and functionally distinct elements or possess a high amount of bits of information. Here, we describe some of the historical arguments that led to the social complexity hypothesis, and review evidence in support of the hypothesis. We discuss social complexity as a driver of communication and possible causal factor in human language origins. Finally, we discuss some of the key current limitations to the social complexity hypothesis—the lack of tests against alternative hypotheses for communicative complexity and evidence corroborating the hypothesis from modalities other than the vocal signalling channel.
Social networks and the development of social skills in cowbirds
Authors: White David J. , Gersick Andrew S. , Snyder-Mackler Noah
Published: May 2012

The complex interrelationships among individuals within social environments can exert selection pressures on social skills: those behaviours and cognitive processes that allow animals to manipulate and out-reproduce others. Social complexity can also have a developmental effect on social skills by providing individuals with opportunities to hone their skills by dealing with the challenges posed in within-group interactions. We examined how social skills develop in captive, adult male brown-headed cowbirds (Molothrus ater) that were exposed to differing levels of ‘social complexity’ across a 2-year experiment. After each year, subjects housed in groups with dynamic social structure (where many individuals entered and exited the groups during the year) outcompeted birds who had been housed in static groups. Exposure to dynamic structure subsequently led to substantial changes to the social networks of the home conditions during the breeding season. Static groups were characterized by a predictable relationship between singing and reproductive success that was stable across years. In dynamic conditions, however, males showed significant variability in their dominance status, their courting and even in their mating success. Reproductive success of males varied dramatically across years and was responsive to social learning in adulthood, and socially dynamic environments ‘trained’ individuals to be better competitors, even at an age when the development of many traits important for breeding (like song quality) had ended.
(4RS)-Methyl 4-cyano-4-cyclohexyl-4-phenylbutanoate
Authors: Sun Gui-Sheng , Hu Yu-Lai , Huang Dan-Feng , Xu Chang-Ming
Published: May 2012

In the crystal structure of the title compound, C18H23NO2, there are only van der Waals interactions present. The cyclohexyl ring has a chair conformation. The longer axes of the displacement parameters of the non-H atoms forming the ethylmethylcarboxylate skeleton are perpendicular to the plane through the non-H atoms of this skeleton.
1-Isopropyl-4,7-dimethyl-2,8-dinitronaphthalene
Authors: Chakkar Mouna , Oughris Najia , Benharref Ahmed , Daran Jean-Claude , Berraho Moha
Published: May 2012

The title compound, C15H16N2O4, was synthesized from a mixture of α-himachalene (2-methylene-6,6,9-trimethylbicyclo[5.4.O1,7]undec-8-ene) and β-himachalene (2,6,6,9-tetramethylbicyclo[5.4.01,7]undeca-1,8-diene) which were isolated from an oil of the Atlas cedar (Cedrus atlantica). The asymmetric unit contains two independent molecules. In each of the two molecules, two O atoms of one nitro group are disordered over two sets of sites with site-occupancy factors of 0.636 (5):0.364 (5) and 0.832 (5):0.168 (5). The crystal structure features weak C—H...O hydrogen bonds.
Dichloridobis[ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate-κ2
O,N
3]cadmium
Authors: Zhang Lai-Jun , Chen Fa-Yun , Liu Guang-Yi , Chen Xiao , Chen Zhi-Feng
Published: May 2012

The asymmetric unit of the title compound, [CdCl2(C7H10N2O2S)2], contains two complex molecules with similar configurations. The CdII atoms are each six-coordinated by two thiazole N and two carbonyl O atoms from the 2-(2-amino-1,3-thiazol-4-yl)acetate ligand, and by two Cl− anions in a distorted octahedral geometry. In the crystal, intra- and intermolecular N—H...Cl hydrogen bonds create parallel chains along [1-10]. C—H...Cl interactions also occur.
Diaquabis(2,2′-bi-1H-imidazole)manganese(II) benzene-1,4-dicarboxylate
Authors: Yang Lining , Zhi Yanxiang , Hei Jiahui , Miao Yanqing
Published: May 2012

The asymmetric unit of the title compound, [Mn(C6H6N4)2(H2O)2](C8H4O4), contains one-half each of the centrosymmetric cation and anion. The MnII atom is coordinated by four N atoms [Mn—N = 2.2168 (14) and 2.2407 (14) Å] from two 2,2′-biimidazole ligands and two water molecules [Mn—O = 2.2521 (14) Å] in a distorted octahedral geometry. Intermolecular N—H...O and O—H...O hydrogen bonds consolidate the crystal packing, which also exhibits π–π interactions between five-membered rings, with a centroid–centroid distance of 3.409 (2) Å.
Poly[(μ2-benzene-1,3-dicarboxylato-κ2
O
1:O
3){μ2-1,2-bis[(1H-imidazol-1-yl)methyl]benzene-κ2
N
3:N
3′}zinc]
Authors: Chen Hong , Xu Heng
Published: May 2012

In the two-dimensional title coordination polymer, [Zn(C8H4O4)(C14H14N4)]
n
, the ZnII atom adopts a distorted tetrahedral geometry, being ligated by two O atoms from two different benzene-1,3-dicarboxylate dianions and two N atoms from two symmetry-related 1,2-bis(imidazol-1-ylmethyl)benzene molecules. The dihedral angles between the imidazole rings and the benzene ring in the neutral ligand are 76.31 (13) and 85.33 (15)°. The ZnII atoms are bridged by dicarboxylate ligands, forming chains parallel to the a axis, which are further linked by 1,2-bis(imidazol-1-ylmethyl)benzene molecules, generating a two-dimensional layer structure parallel to the ac plane. The crystal structure is enforced by intralayer and interlayer C—H...O hydrogen bonds.
Tetra-μ3-iodido-tetrakis{[ethyl 2-(1H-benzimidazol-1-yl)acetate-κN
3]copper(I)}
Authors: Yang Lili , Zhang Zhengyi
Published: May 2012

The complex molecule of the tetranuclear cubane-type title compound, [Cu4I4(C11H12N2O2)4], has crystallographically imposed fourfold inversion symmetry. The CuI ions are coordinated in a distorted tetrahedral geometry by an N atom of a benzimidazole ring system and three μ3-iodide ions, forming a Cu4I4 core. In the crystal, complex molecules are connected into a three-dimensional network by C—H...O hydrogen bonds involving H and O atoms of adjacent ethoxycarbonyl groups.
Poly[[tetraaquabis(μ3-5-carboxybenzene-1,2,4-tricarboxylato)tricadmium] tetrahydrate]
Authors: Jia Yong-Yan , Xie Xin-Nian , Yang Huai-Xia
Published: May 2012

There are three independent CdII ions in the title complex, {[Cd3(C10H3O8)2(H2O)4]·4H2O}
n
, one of which is coordinated by four O atoms from three 5-carboxybenzene-1,2,4-tricarboxylate ligands and by two water molecules in a distorted octahedral geometry. The second CdII ion is coordinated by five O atoms from four 5-carboxybenzene-1,2,4-tricarboxylate ligands and by one water molecule also in a distorted octahedral geometry while the third CdII ion is coordinated by five O atoms from three 5-carboxybenzene-1,2,4-tricarboxylate ligands and by one water molecule in a highly distorted octahedral geometry. The 5-carboxybenzene-1,2,4-tricarboxylate ligands bridge the CdII ions, resulting in the formation of a three-dimensional structure. Intra- and intermolecular O—H...O hydrogen bonds are present throughout the three-dimensional structure.