bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical design of the short pulse x-ray imaging and microscopy time-angle correlated diffraction beamline at the Advanced Photon Source
Authors: Reininger R. , Dufresne E. M. , Borland M. , Beno M. A. , Young L. , Kim K.-J. , Evans P. G.
Published: May 2013

The short pulse x-ray imaging and microscopy beamline is one of the two x-ray beamlines that will take full advantage of the short pulse x-ray source in the Advanced Photon Source (APS) upgrade. A horizontally diffracting double crystal monochromator which includes a sagittally focusing second crystal will collect most of the photons generated when the chirped electron beam traverses the undulator. A Kirkpatrick-Baez mirror system after the monochromator will deliver to the sample a beam which has an approximately linear correlation between time and vertical beam angle. The correlation at the sample position has a slope of 0.052 ps/μrad extending over an angular range of 800 μrad for a cavity deflection voltage of 2 MV. The expected time resolution of the whole system is 2.6 ps. The total flux expected at the sample position at 10 keV with a 0.9 eV energy resolution is 5.7 × 1012 photons/s at a spot having horizontal and vertical full width at half maximum of 33 μm horizontal by 14 μm vertical. This new beamline will enable novel time-dispersed diffraction experiments on small samples using the full repetition rate of the APS.
Thermal conductivity dependence on chain length in amorphous polymers
Authors: Zhao Junhua , Jiang Jin-Wu , Wei Ning , Zhang Yancheng , Rabczuk Timon
Published: May 2013

We apply united-atom (UA) nonequilibrium molecular dynamics simulations to predict the thermal conductivity for amorphous polyethylene at room temperature with chain length (CL) increasing from 4 to 1260. The thermal conductivity is determined by the competition of the two mechanisms: (1) The collision among the UA beads and (2) the phonon vibration. The collision mechanism mainly dominates CL≤7, while the phonon vibration mechanism mainly determines CL ≥ 140. The competition between the two mechanisms determines 12 ≤ CL ≤ 140. In particular, the thermal conductivity for 8 ≤ CL ≤ 11 cannot be obtained accurately due to the aggregation of the beads.
Coexistence of intrinsic and extrinsic origins of room temperature ferromagnetism in as implanted and thermally annealed ZnO films probed by x-ray absorption spectroscopy
Authors: Satyarthi P. , Ghosh S. , Pandey B. , Kumar P. , Chen C. L. , Dong C. L. , Pong W. F. , Kanjilal D. , Asokan K. , Srivastava P.
Published: May 2013

The present work reports the structural and ferromagnetic properties of 200 KeV Ni2+ ion implanted ZnO films before and after annealing at 650 °C in air and correlates these properties with their electronic structures. X-ray absorption spectroscopy (XAS) at Zn and Ni K-edges reveal that Zn metal cluster is absent in ZnO matrix, but there is an indication of clustering of Ni metal as a secondary phase. The XAS analysis of O K-edge shows (i) non-stoichiometric NiO segregation in as-implanted film and its absence/reduction in air annealed film, (ii) partial substitution of Ni2+ ions at tetrahedral Zn sites, and (iii) presence of lattice defects such as oxygen vacancies in both films. The observed ferromagnetic behavior of as-implanted and air annealed films has both intrinsic as well as extrinsic origins. The intrinsic and extrinsic origins are discussed in terms of bound magnetic polaron model and presence of antiferromagnetic NiO phase/ferromagnetic Ni metal clusters, respectively.
Growth, microstructure, and luminescent properties of direct-bandgap InAlP on relaxed InGaAs on GaAs substrates
Authors: Mukherjee K. , Beaton D. A. , Christian T. , Jones E. J. , Alberi K. , Mascarenhas A. , Bulsara M. T. , Fitzgerald E. A.
Published: May 2013

Direct-bandgap InAlP alloy has the potential to be an active material in nitride-free yellow-green and amber optoelectronics with applications in solid-state lighting, display devices, and multi-junction solar cells. We report on the growth of high-quality direct-bandgap InAlP on relaxed InGaAs graded buffers with low threading dislocation densities. Structural characterization reveals phase-separated microstructures in these films which have an impact on the luminescence spectrum. While similar to InGaP in many ways, the greater tendency for phase separation in InAlP leads to the simultaneous occurrence of compositional inhomogeneity and CuPt-B ordering. Mechanisms connecting these two structural parameters are presented as well as results on the effect of silicon and zinc dopants on homogenizing the microstructure. Spontaneous formation of tilted planes of phase-separated material, with alternating degrees of ordering, is observed when InAlP is grown on vicinal substrates. The photoluminescence peak-widths of these films are actually narrower than those grown on exact (001) substrates. We find that, despite phase-separation, ordered direct-bandgap InAlP is a suitable material for optoelectronics.
Magnetic force microscopy study of the switching field distribution of low density arrays of single domain magnetic nanowires
Authors: Tabasum M. R. , Zighem F. , De La Torre Medina J. , Encinas A. , Piraux L. , Nysten B.
Published: May 2013

In the present work, we report on the in situ magnetic force microscopy (MFM) study of the magnetization reversal in two-dimensional arrays of ferromagnetic Ni80Fe20 and Co55Fe45 nanowires (NW) with different diameters (40, 50, 70, and 100 nm) deposited inside low porosity (P < 1%) nanoporous polycarbonate membranes. In such arrays, the nanowires are sufficiently isolated from each other so that long range dipolar interactions can be neglected. The MFM experiments performed for different magnetization states at the same spot of the samples are analysed to determine the switching field distribution (SFD). The magnetization curves obtained from the MFM images are relatively square shaped. The SFD widths are narrower compared to those obtained for high density arrays. The weak broadening of the curves may be ascribed to the NW intrinsic SFD. The influence of diameter and composition of the ferromagnetic NW is also investigated.
Critical exponents and irreversibility lines of La0.9Sr0.1CoO3 single crystal
Authors: Khan N. , Midya A. , Mandal P. , Prabhakaran D.
Published: May 2013

We have studied the dynamic and static critical behavior of spin glass transition in insulating La0.9Sr0.1CoO3 single crystal by ac susceptibility and dc magnetization measurements in the vicinity of its freezing temperature (Tf). The dynamic scaling analysis of the frequency dependence of ac susceptibility data yields the characteristic time constant τ0=1.6(9)×10−12 s, the dynamic critical exponent zν=9.5(2), and a frequency dependence factor K=ΔTf/Tf(Δlogf)=0.017, indicating that the sample enters into a canonical spin-glass phase below Tf = 34.8(2) K. The scaling analysis of non-linear magnetization in the vicinity of Tf through the static scaling hypothesis yields critical exponents β = 0.89(1) and γ = 2.9(1), which match well with that observed for well known three-dimensional (3D) Heisenberg spin glasses. From the longitudinal component of zero-field-cooled and field-cooled magnetization measurement, we have constructed the H–T phase diagram which represents the field evolution of two characteristic temperatures: the upper one, Tw(H), indicates the onset of spin freezing in a uniform external field H, while the lower one, Ts(H), marks the onset of strong irreversibility of the frozen state. The low field Ts(H) follows the critical line suggested by d'Almeida-Thouless model for canonical spin glass, whereas the Tw(H) exhibits a re-entrant behavior with a maximum in the Tw(H) at a nonzero field above which it follows the Gabay-Toulouse (GT) critical line which is a characteristic of Heisenberg spin glass. The reentrant behavior of the GT line resembles that predicted theoretically for n-component vector spin glasses in the presence of a uniaxial anisotropy field.
Interspacing dependence of spin-dependent variable range hopping for cold-pressed Fe3O4 nanoparticles
Authors: Song Ning-Ning , Yang Hai-Tao , Li Fei-Ye , Li Zi-An , Han Wei , Ren Xiao , Luo Yi , Wang Xian-Cheng , Jin Chang-Qing , Zhang Xiang-Qun , Cheng Zhao-Hua
Published: May 2013

The influence of the contact between monodisperse Fe3O4 nanoparticles (NPs) on the spin-dependent transport mechanism has been investigated by only changing the cold-press pressures from 20.0 MPa to 5.0 GPa. For the sample cold-pressed under 20.0 MPa, the temperature dependence of resistivity ρ-T curve is best fitted by the log ρ ∝ T−1/2 relation, suggesting the Efros's variable range hopping (VRH) mechanism, while the ρ-T curves of the samples cold-pressed under 1.0 GPa to 5.0 GPa can be best fit with the relation of log ρ ∝ T−1/4, revealing the Mott's VRH mechanism. The different mechanisms are related to the interspacing dependence of charging energy and exchange energy between NPs. Monte Carlo simulations indicated that the charging energy plays a dominant role in the former mechanism, while the spin-dependent exchange energy is dominated in the latter one.
Comparisons of angularly and spectrally resolved Bremsstrahlung measurements to two-dimensional multi-stage simulations of short-pulse laser-plasma interactions
Authors: Chen C. D. , Kemp A. J. , Pérez F. , Link A. , Beg F. N. , Chawla S. , Key M. H. , McLean H. , Morace A. , Ping Y. , Sorokovikova A. , Stephens R. B. , Streeter M. , Westover B. , Patel P. K.
Published: May 2013

A 2-D multi-stage simulation model incorporating realistic laser conditions and a fully resolved electron distribution handoff has been developed and compared to angularly and spectrally resolved Bremsstrahlung measurements from high-Z planar targets. For near-normal incidence and 0.5-1 × 1020 W/cm2 intensity, particle-in-cell (PIC) simulations predict the existence of a high energy electron component consistently directed away from the laser axis, in contrast with previous expectations for oblique irradiation. Measurements of the angular distribution are consistent with a high energy component when directed along the PIC predicted direction, as opposed to between the target normal and laser axis as previously measured.
Frequency shift of the propagating ultraintense field in a plasma with a fraction of electron-positron pairs under the conditions of response saturation
Authors: Shiryaev O. B.
Published: May 2013

A model is derived from the Maxwell and fluid dynamics equations to describe the interactions between a relativistically intense electromagnetic wave and a cold unmagnetized plasma composed of an electron-ion background and a fraction of electron-positron pairs. Combining the envelope approximation for the propagating field and the quasistatic treatment of the plasma dynamics, the model sustains fully nonlinear plane-wave solutions and shows that saturation of the plasma response occurs at ultrarelativistic intensities of the incident field even for pair concentrations far below those of the electron-ion background. Stability of the electromagnetic wave under the saturation conditions is demonstrated and an expression is derived to link its interaction-induced frequency shift to the concentration of the electron-positron pairs.
Intersubband plasmon-phonon coupling in GaAsP/AlGaAs near surface quantum well
Authors: Aggarwal R. , Ingale Alka A. , Pal Suparna , Dixit V. K. , Sharma T. K. , Oak S. M.
Published: May 2013

The investigation of electron-phonon coupling in near surface GaAs1−xPx/AlyGa1−yAs quantum well structures using wavelength and intensity dependent Raman spectroscopy shows that in the near surface quantum well case, coupled modes are situated at the frequency between longitudinal optical (LO) and transverse optical phonons of GaAsP, which is forbidden for the coupled electron-phonon modes in the bulk ternary alloy. The observed “GaAs like” and “GaP like” LO phonon-intersubband plasmon coupled mode frequencies decrease with increase in carrier density. These results corroborate well with the theoretical calculation for variation of two dimensional electron gas-phonon coupling with carrier density in ternary alloys.
Influence of excess SrO on the thermoelectric properties of heavily doped SrTiO3 ceramics
Authors: Wang Yifeng , Wan Chunlei , Zhang Xiaoyan , Shen Liming , Koumoto Kunihito , Gupta Arunava , Bao Ningzhong
Published: May 2013

The effects of excess SrO on the thermoelectric properties of n-type SrTiO3 have been investigated through a comparative study of different polycrystalline ceramic samples. These include Gd-doped SrTiO3 with varying SrO, nominally in the form of Ruddlesden-Popper phase of SrO(SrTiO3)n with n = 5, 10, and 20, and previously reported analogues with n = 1, 2, and ∞ (i.e., stoichiometric SrTiO3). As compared with stoichiometric SrTiO3, with increasing SrO excess (i.e., decreasing n value), the electrical conductivity is found to decrease more substantially than the thermal conductivity, while the Seebeck coefficient remains almost unaffected with n in the range of 5–20.
Spontaneous electromagnetic fluctuations in unmagnetized plasmas. II. Relativistic form factors of aperiodic thermal modes
Authors: Felten T. , Schlickeiser R. , Yoon P. H. , Lazar M.
Published: May 2013

General expressions for the electromagnetic fluctuation spectra in unmagnetized plasmas are derived using fully relativistic dispersion functions and form factors for the important class of isotropic plasma particle distribution functions including in particular relativistic Maxwellian distributions. In order to obtain fluctuation spectra valid in the entire complex frequency plane, the proper analytical continuations of the unmagnetized form factors and dispersion functions are presented. The results are illustrated for the important special case of isotropic Maxwellian particle distribution functions providing in particular the thermal fluctuations of aperiodic modes. No restriction to the plasma temperature value is made, and the electromagnetic fluctuation spectra of ultrarelativistic thermal plasmas are calculated. The fully relativistic calculations also provide more general results in the limit of nonrelativistic plasma temperatures being valid in the entire complex frequency plane. They complement our earlier results in paper I and III of this series for negative values of the imaginary part of the frequency. A new collective, transverse, damped aperiodic mode with the damping rate γ∝−k−5/3 is discovered in an isotropic thermal electron-proton plasma with nonrelativistic temperatures.
The physics of tokamak start-up
Authors: Mueller D.
Published: May 2013

Tokamak start-up on present-day devices usually relies on inductively induced voltage from a central solenoid. In some cases, inductive startup is assisted with auxiliary power from electron cyclotron radio frequency heating. International Thermonuclear Experimental Reactor, the National Spherical Torus Experiment Upgrade and JT60, now under construction, will make use of the understanding gained from present-day devices to ensure successful start-up. Design of a spherical tokamak (ST) with DT capability for nuclear component testing would require an alternative to a central solenoid because the small central column in an ST has insufficient space to provide shielding for the insulators in the solenoid. Alternative start-up techniques such as induction using outer poloidal field coils, electron Bernstein wave start-up, coaxial helicity injection, and point source helicity injection have been used with success, but require demonstration of scaling to higher plasma current.
Low-resistivity, high-transmittance Ga:ZnO films prepared through metalorganic chemical vapor deposition using an inexpensive solution of diethylzinc in n-hexane as the Zn precursor
Authors: Giang Nguyen Nam , Thanh Ho Van Thi , Hong Lu-Sheng
Published: May 2013

In this study, we prepared Ga-doped ZnO (GZO) films with qualified opto-electric properties through chemical vapor deposition of an inexpensive solution of diethylzinc in n-hexane (ca. 17 wt. %). The GZO films exhibited low resistivity (3.61 × 10−4 Ω cm) and high transmittance (85%) in the visible range. Interestingly, post-annealing treatment of the GZO films under N2 at 525 °C for just 10 min increased the number of carbon-interstitial oxygen defects (CZn + 2Oi)″, which played the role of acceptors and enhanced the film properties significantly. This approach potentially allows the fabrication of inexpensive transparent conducting oxides for use in solar cells.
Communication: Electronic structure of the solvated chloride anion from first principles molecular dynamics
Authors: Zhang Cui , Pham Tuan Anh , Gygi François , Galli Giulia
Published: May 2013

We present first principles molecular dynamics simulations of the chloride anion in liquid water performed using gradient-corrected and hybrid density functionals. We show that it is necessary to use hybrid functionals both for the generation of molecular dynamics trajectories and for the calculation of electronic states in order to obtain a qualitatively correct description of the electronic properties of the solution. In particular, it is only with hybrid functionals that the highest occupied molecular orbital of the anion is found above the valence band maximum of water, consistent with photoelectron detachment measurements. Similar results were obtained using many body perturbation theory within the G0W0 approximation.
Controlled softening of Cu64Zr36 metallic glass by ion irradiation
Authors: Avchaciov K. A. , Ritter Y. , Djurabekova F. , Nordlund K. , Albe K.
Published: May 2013

We study the effect of irradiation with 5–20 keV recoils on the topological and chemical short-range order of Cu64Zr36 metallic glass using molecular dynamics simulations. We show that within the cascade region, the structural backbone of stiff Cu-centered icosahedral units is destroyed, leading to locally softened areas. Under mechanical load, the formation of shear transformation zones is thus promoted in the damaged area. Our results suggest that irradiation is a means to introduce nucleation sites for multiple shear bands and thus prevents catastrophic failure due to the presence of a single critical shear band.
Elastic properties of tetragonal BiFeO3 from first-principles calculations
Authors: Dong Huafeng , Chen Changqing , Wang Shanying , Duan Wenhui , Li Jingbo
Published: May 2013

Multiferroic BiFeO3 can exist in tetragonal G-type and C-type antiferromagnetic phases with a giant c/a ratio and polarizability. In this letter, the elastic constants cij's of these tetragonal BiFeO3 phases are studied as the function of pressure using first-principles density-functional theory. We find that, except for c44, the predicted cij's decrease with decreasing pressure (or increasing volume). When the volume is less than 11 Å3/atom (or greater than 17 Å3/atom), the c44 of these tetragonal phases tend to zero and the structures become unstable. The tetragonal phases are predicted to be softer than the rhombohedral antiferromagnetic phase. Other elastic properties, including bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and elastic anisotropy ratios are also investigated.
La doped SrTiO3 thin films on SrLaAlO4 (001) as transparent conductor
Authors: Biswas A. , Li N. , Jung M. H. , Lee Y. W. , Kim J. S. , Jeong Y. H.
Published: May 2013

Transparent conductors are essential for many optoelectronic applications, and economically viable replacement for the industry standard transparent conductor, indium tin oxide, is in dire need. Electronic structure calculations are performed to confirm that La doping in a band insulator SrTiO3 provides carriers in the conduction band without generating in-gap states and thus La doped SrTiO3 would retain good optical transparency. To realize the computational results, we synthesize La doped SrTiO3 in thin film form and characterize the films. It is demonstrated that 10% La doped SrTiO3 thin films on SrLaAlO4 (001) substrates are indeed transparent conductors with sheet resistance RS ∼ 60 Ω/◻ and 80% transmission in the visible wavelength range at room temperature.
Investigation of size and electronic effects on Kapitza conductance with non-equilibrium molecular dynamics
Authors: Jones R. E. , Duda J. C. , Zhou X. W. , Kimmer C. J. , Hopkins P. E.
Published: May 2013

In nanosystems, the thermal resistance between materials typically dominates the overall resistance. While size effects on thermal conductivity are well documented, size effects on thermal boundary conductance have only been speculated. In response, we characterize the relationship between interfacial resistance and material dimension using molecular dynamics. We find that the interfacial resistance increases linearly with inverse system length but is insensitive to cross-sectional area. Also, from the temperature-dependence of interfacial resistance, we conclude that contributions of short-wavelength phonons dominate. Lastly, by coupling the molecular dynamics to a two-temperature model, we show that electron-mediated transport has little effect on thermal resistance.
Influence of the transparent conductive oxide layer deposition step on electrical properties of silicon heterojunction solar cells
Authors: Favre W. , Coignus J. , Nguyen N. , Lachaume R. , Cabal R. , Muñoz D.
Published: May 2013

This work deals with the understanding of the transport behavior of different deposited Indium Tin Oxide (ITO) layers on the emitter of n-type heterojunction solar cells. A complete study based on effective lifetime measurements has been carried out on samples with different ITO thicknesses to evaluate the passivation quality before and after ITO deposition, showing that increasing the ITO thickness degrades the passivation properties only at low injection level. Further characterizations coupled with numerical simulations demonstrate that such a behavior is due to recombination at the ITO/(p) a-Si:H interface induced by the ITO layer.
Electrochemical analysis of transparent oxide-less photovoltaic cell with perforation patterned metal substrate
Authors: Kim Myoung , You In-Kyu , Lee Kyoung-Won , Lee In-Hwan , Yun Ho-Gyeong
Published: May 2013

In terms of electrochemical behaviour, a transparent conductive oxide (TCO)-less dye-sensitized solar cell (DSSC) with two metal foils was compared with those of a metal foil-based DSSC with a TCO-coated substrate. By virtue of electrochemical impedance spectroscopy, intensity modulated photocurrent spectroscopy, intensity modulated photovoltage spectroscopy, open-circuit voltage decay, and photocurrent transient measurements, it was clearly confirmed that the limited performance of the TCO-less DSSC was caused by the restricted transport of ion species in the electrolyte due to the perforation patterned metal foil.
Temperature dependence of the average electron-hole pair creation energy in Al0.8Ga0.2As
Authors: Barnett A. M. , Lees J. E. , Bassford D. J.
Published: May 2013

The temperature dependence of the average energy consumed in the creation of an electron-hole pair in the wide bandgap compound semiconductor Al0.8Ga0.2As is reported following X-ray measurements made using an Al0.8Ga0.2As photodiode diode coupled to a low-noise charge-sensitive preamplifier operating in spectroscopic photon counting mode. The temperature dependence is reported over the range of 261 K–342 K and is found to be best represented by the equation εAlGaAs = 7.327–0.0077 T, where εAlGaAs is the average electron-hole pair creation energy in eV and T is the temperature in K.
Methanol incorporation in clathrate hydrates and the implications for oil and gas pipeline flow assurance and icy planetary bodies
Authors: Shin Kyuchul , Udachin Konstantin A. , Moudrakovski Igor L. , Leek Donald M. , Alavi Saman , Ratcliffe Christopher I. , Ripmeester John A.
Published: May 2013

One of the best-known uses of methanol is as antifreeze. Methanol is used in large quantities in industrial applications to prevent methane clathrate hydrate blockages from forming in oil and gas pipelines. Methanol is also assigned a major role as antifreeze in giving icy planetary bodies (e.g., Titan) a liquid subsurface ocean and/or an atmosphere containing significant quantities of methane. In this work, we reveal a previously unverified role for methanol as a guest in clathrate hydrate cages. X-ray diffraction (XRD) and NMR experiments showed that at temperatures near 273 K, methanol is incorporated in the hydrate lattice along with other guest molecules. The amount of included methanol depends on the preparative method used. For instance, single-crystal XRD shows that at low temperatures, the methanol molecules are hydrogen-bonded in 4.4% of the small cages of tetrahydrofuran cubic structure II hydrate. At higher temperatures, NMR spectroscopy reveals a number of methanol species incorporated in hydrocarbon hydrate lattices. At temperatures characteristic of icy planetary bodies, vapor deposits of methanol, water, and methane or xenon show that the presence of methanol accelerates hydrate formation on annealing and that there is unusually complex phase behavior as revealed by powder XRD and NMR spectroscopy. The presence of cubic structure I hydrate was confirmed and a unique hydrate phase was postulated to account for the data. Molecular dynamics calculations confirmed the possibility of methanol incorporation into the hydrate lattice and show that methanol can favorably replace a number of methane guests.
iFUSE: integrated fusion gene explorer
Authors: Hiltemann Saskia , McClellan Elizabeth A. , van Nijnatten Jos , Horsman Sebastiaan , Palli Ivo , Teles Alves Ines , Hartjes Thomas , Trapman Jan , van der Spek Peter , Jenster Guido , Stubbs Andrew
Published: May 2013

Summary: We present iFUSE (integrated fusion gene explorer), an online visualization tool that provides a fast and informative view of structural variation data and prioritizes those breaks likely representing fusion genes. This application uses calculated break points to determine fusion genes based on the latest annotation for genomic sequence information, and where relevant the structural variation (SV) events are annotated with predicted RNA and protein sequences. iFUSE takes as input a Complete Genomics (CG) junction file, a FusionMap fusion detection report file or a file already analysed and annotated by the iFUSE application on a previous occasion.

Results: We demonstrate the use of iFUSE with case studies from tumour-normal SV detection derived from Complete Genomics whole-genome sequencing results.

Availability: iFUSE is available as a web service at http://ifuse.erasmusmc.nl.

Contact: s.hiltemann@erasmusmc.nl or a.stubbs@erasmusmc.nl
Adaptive reference-free compression of sequence quality scores
Authors: Janin Lilian , Rosone Giovanna , Cox Anthony J.
Published: May 2013

Motivation: Rapid technological progress in DNA sequencing has stimulated interest in compressing the vast datasets that are now routinely produced. Relatively little attention has been paid to compressing the quality scores that are assigned to each sequence, even though these scores may be harder to compress than the sequences themselves. By aggregating a set of reads into a compressed index, we find that the majority of bases can be predicted from the sequence of bases that are adjacent to them and, hence, are likely to be less informative for variant calling or other applications. The quality scores for such bases are aggressively compressed, leaving a relatively small number at full resolution. As our approach relies directly on redundancy present in the reads, it does not need a reference sequence and is, therefore, applicable to data from metagenomics and de novo experiments as well as to re-sequencing data.

Results: We show that a conservative smoothing strategy affecting 75% of the quality scores above Q2 leads to an overall quality score compression of 1 bit per value with a negligible effect on variant calling. A compression of 0.68 bit per quality value is achieved using a more aggressive smoothing strategy, again with a very small effect on variant calling.

Availability: Code to construct the BWT and LCP-array on large genomic data sets is part of the BEETL library, available as a github repository at git@github.com:BEETL/BEETL.git.

Contact:  acox@illumina.com
CMAP: Complement Map Database
Authors: Yang Kun , Dinasarapu Ashok R. , Reis Edimara S. , DeAngelis Robert A. , Ricklin Daniel , Subramaniam Shankar , Lambris John D.
Published: May 2013

Summary: The human complement system is increasingly perceived as an intricate protein network of effectors, inhibitors and regulators that drives critical processes in health and disease and extensively communicates with associated physiological pathways ranging from immunity and inflammation to homeostasis and development. A steady stream of experimental data reveals new fascinating connections at a rapid pace; although opening unique opportunities for research discoveries, the comprehensiveness and large diversity of experimental methods, nomenclatures and publication sources renders it highly challenging to keep up with the essential findings. With the Complement Map Database (CMAP), we have created a novel and easily accessible research tool to assist the complement community and scientists from related disciplines in exploring the complement network and discovering new connections.

Availability:  http://www.complement.us/cmap.

Contact:  lambris@upenn.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Oil price shocks and stock market behaviour in Nigeria
Authors: Adetunji Babatunde Musibau , Adenikinju Olayinka , Adenikinju Adeola F.
Published: May 2013

Purpose

The purpose of this study is to investigate the interactive relationships between oil price shocks and the Nigeria stock market.

Design/methodology/approach

The paper applied the multivariate vector auto‐regression that employed the generalized impulse response function and the forecast variance decomposition error.

Findings

Empirical evidence reveals that stock market returns exhibit insignificant positive response to oil price shocks but reverts to negative effects after a period of time depending on the nature of the oil price shocks. The results are similar even with the inclusion of other variables. Also, the asymmetric effect of oil price shocks on the Nigerian stock returns indices is not supported by statistical evidences.

Originality/value

This is the first study to examine the dynamic linkages between stock market behaviour and oil price shocks in Nigeria.
Balance‐of‐payments‐constrained growth in a multisectoral framework
Authors: Rocha Gouvêa Raphael , Tadeu Lima Gilberto
Published: May 2013

Purpose

The aim of this paper is to contribute to the literature on balance‐of‐payments‐constrained growth by providing an innovative empirical evaluation of a disaggregated version of the so‐called Thirlwall's Law derived from a Pasinettian multisectoral framework.

Design/methodology/approach

After estimating sectoral elasticities of exports and imports for a considerable panel dataset of 90 countries over the period 1965‐1999, the authors have performed two empirical exercises. First, they grouped countries together by income level and evaluated a multisectoral balance‐of‐payments‐constrained growth model by analyzing prediction errors and mean absolute deviations. Second, the authors carried out a regression validity test on the results.

Findings

The main findings give support to the validity of the multisectoral version of Thirlwall's Law, providing therefore further understanding of the structural determinants of the uneven international development and guidance for the design of growth‐enhancing national structural policies.

Originality/value

The main value added of this contribution to the existing literature lies in the use of disaggregated trade data in conjunction with modern panel data econometric techniques to obtain empirical estimates on the balance‐of‐payments constraints to long‐run economic growth for an unprecedently large sample of countries.
South American immigrants in the USA
Authors: Medina Carlos , Posso Christian
Published: May 2013

Purpose

The purpose of this paper is to examine the main factors influencing the decision of migrants from South America (SA) living in the USA to return to their countries of origin. In particular, it is aimed at understanding the role played by higher education in this decision. Although it is not feasible to refer to the tasks performed by immigrants in the USA as determinants in their decision to return to their homelands, it is nonetheless worth verifying whether these tasks are closely related or not to their qualifications.

Design/methodology/approach

The program evaluation methodology proposed by Heckman and Robb to correct the “contamination bias” in a program evaluation setting is adopted in this document.

Findings

This exercise shows that the probability of remaining in the USA for those with university degrees or more advanced education levels is 12.6 percent higher than for those with only secondary or lower education. In addition, it is shown that SA immigrants are usually engaged in tasks requiring certain qualifications commensurate with their level of education, although such relationship varies in intensity among migrants from different countries.

Research limitations/implications

This exercise does not take into account migrants in the USA not included in the US Censuses.

Practical implications

The results obtained mean that the flight of human capital from SA countries to the USA is being accentuated by the “negative selection” of returnees, and that migrants' qualifications actually determine the complexity of tasks they may perform in the USA.

Originality/value

The paper overcomes the lack of longitudinal data of migrants by implementing a methodology providing new evidence about return migration and brain drain of SA immigrants in the USA. In addition, new data are used to analyze the relationship between education and the complexity of the tasks SA migrants are performing in the USA.
Challenges and developments of micro drill bit for printed circuit board: a review
Authors: Shi Hongyan , Li Hui
Published: May 2013

Purpose

The purpose of this paper is to present a clear picture of the challenges of micro drill bit and the developments of novel micro‐drill bits for flexible circuit boards, environmental‐friendly printed circuit boards (PCBs), high aspect ratio drill bit and ultra‐small micro drill bit, as well as the developments of geometry design of micro drill bit.

Design/methodology/approach

The paper details the developments trend and challenges of micro drill and PCBs first. Then the current research status of novel micro drill bits for flexible circuit boards, environmental‐friendly PCBs, high aspect ratio drill bit, ultra‐small micro drill bit are described. Finally, the developments of geometry design and drilling process are reviewed.

Findings

To achieve excellent performance for drilling flexible PCB, a large helical angle, large flute/land ratio and small web thickness that guarantee the sharp evacuation capability, are adopted in drill bit design. A small helix angle and an appropriate primary face angle are employed for drill bit to process environmental‐friendly printed circuit boards. It is beneficial to implement big helix angle, small primary face angles and small point angles in the design of ultra‐small micro drill bit. An optimum web thickness and step feed should be taken into consideration in high aspect ratio drill bits design.

Originality/value

The paper reviews different solutions of micro drill bits for the state‐of‐the‐art PCB and the developments of geometry design of drill bit for printed circuit boards.
Micro UHMW‐PE column array molded by the utilization of PCB as mold insert
Authors: Liang Xiong , Li Bing , Wu Xiaoyu , Shi Hongyan , Zeng Kun , Wang Yatao
Published: May 2013

Purpose

The purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which micro‐hole arrays are drilled is used as a micro cavity insert. With the utilization of ultrasonic vibration, the polymer powder, which is prefilled and compacted in a micro cavity, mutually generates great sliding friction heat so as to be rapidly plasticized and molded.

Design/methodology/approach

Micro carbide drill bits of which the diameters are 100.0 μm, 150.0 μm and 200.0 μm, respectively, are used for drilling the PCB to form a micro‐hole array insert. Next, two kinds of various ultra‐high molecule weight polyethylene (UHMW‐PE) powder with various grain diameters are directly filled into a charging barrel and a mold cavity with the micro‐hole array insert. Proper process parameters are set on ultrasonic plasticizing and molding equipment so that a molding test can be performed. The melt of UHMW‐PE can be rapidly filled into the cavity. Finally, micro‐column array plastic parts are successfully prepared.

Findings

The micro‐hole array PCB is a mold insert which is quite applicable for the ultrasonic molding of the powder in the mold. When a molding material is the coarse UHMW‐PE powder with the grain diameter of about 350 μm, the diameter replication rates of the micro‐column array plastic parts become good in order with the increased micro‐hole diameter of the PCB. When the fine UHMW‐PE powder with the grain diameter of about 80 μm is adopted, the diameter replication rates of the micro‐column array plastic parts become good in order with the decreased micro‐hole diameter of the PCB.

Originality/value

In this paper, the micro‐column array plastic parts with good replicability are successfully prepared by a technique for ultrasonically plasticizing and molding in the cavity. The technique can be applied to the fields of medical treatment, communication, optics, chemistry and so on, such as biological micro needle arrays, micro biological chips, optical memories, and micro chemical reaction chips.
Effects of UV‐B irradiation on poly (vinyl alcohol) and Ixora siamensis anthocyanins‐coated glass
Authors: Mat Nor N.A. , Aziz N. , Mohd‐Adnan A.F. , Taha R.M. , Arof A.K.
Published: May 2013

Purpose

The purpose of this paper is to evaluate the potential of natural colourants from fruits of Ixora siamensis for coating applications, to study its glossiness and effectiveness against UV‐B irradiation.

Design/methodology/approach

In this study, natural colourants from the fruits of Ixora siamensis were extracted using trifluoroacetic acid‐methanol solution. Anthocyanins and organic acid variants were mixed together to form co‐pigments. Different concentrations of ferulic and gallic acid co‐pigments were added to a blended solution of poly (vinyl alcohol), PVA and anthocyanin (from Ixora siamensis) to form a coating system. The coatings were exposed to UV‐B irradiation at room temperature in air using a UV‐lamp which emitted radiation at 312 nm. The effects of UV‐B irradiation on the coating system were evaluated using glossiness test and UV‐visible spectroscopy.

Findings

Anthocyanins are unstable and can quickly lose their colour. One of the methods of preserving the stability of these pigments is by co‐pigmentation. Co‐pigmentation of anthocyanin with organic acid variants resulted in an increase in both hyperchromic effects (ΔA) and bathochromic shifts (Δλ). In this study, ferulic acids yielded better results compared to gallic acids.

Research limitations/implications

Samples with co‐pigmentation give better result compared to the untreated samples. The addition of 0.5 and 1.0 per cent ferulic acid improves the gloss properties and resistivity of the samples towards the UV irradiation. Thus, in order to study the effectiveness of ferulic acid as additive and improving the properties of the samples, the percentage of ferulic acid added and exposure time could be increased.

Practical implications

The method developed provided a simple and efficient solution for improving the UV resistance of anthocyanin blend with poly (vinyl alcohol), PVA UV absorber. Effect of ferulic acid as UV absorber, if added in more concentration, can be further studied for optimization.

Social implications

The social implication is the use of local plant species as a low cost source of natural pigments in coating system.

Originality/value

The method for improving the resistance towards UV irradiation of anthocyanin blend with poly (vinyl alcohol), PVA was novel and could find numerous applications for natural product based on plant pigment.
Synthesis and characterization of poly(etherfattyamide) coatings from non edible seed oil
Authors: Alam Manawwer , Al‐Andis Naser M.
Published: May 2013

Purpose

The purpose of this study is to develop poly(etherfattyamide) coatings from Pongamia glabra seeds oil utilizing a sustainable resource, which is non edible, non medicinal and goes as waste. Seed oil based poly(etherfattyamide) is used as a coating material to improve the coating properties especially gloss and alkali resistance.

Design/methodology/approach

Pongamia glabra oil was first converted into N,N′ bis 2‐hydroxyethyl Pongamia glabra oil fatty amide (HEPFA). HEPFA was treated with 1,4‐cyclohexanedimethanol (CHDM) to develop poly(etherfattyamide) (PEFA). PEFA was cured with (butylated melamine formaldehyde) (BMF) in different (35, 40, 45, 50) phr (part per hundred part of resin) to produce coating material. The structural elucidations of HEPFA and PEFA were carried out by FT‐IR, 1H‐NMR and 13C‐NMR spectral techniques. The thermal study was performed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The physico‐mechanical and chemical resistance/anticorrosive properties were investigated by standard laboratory methods.

Findings

The authors developed a good coatings material from a sustainable resource. The physico‐mechanical and anticorrosive performance evaluation exhibits satisfactory results. PEFA‐BMF coatings material showed good alkali resistance and high gloss. The thermal studies showed that PEFA‐BMF45 may be safely used up to 225°C.

Practical implications

BMF modified PEFA coatings showed the highest scratch hardness 3.5 kg, flexibility (1/8 inch conical mandrel bend test) and gloss at 45° is 76‐82. Among all, PEFA‐BMF45 showed the best physico‐mechanical and chemical resistance performance. Thus, it may be used as an efficient coating material.

Originality/value

The synthesis of BMF modified PEFA from Pongamia glabra oil using 1,4‐cyclohexanedimethanol has been studied for the first time providing a new approach to utilize a non edible seed oil – a sustainable resource.
Managing teaching and R&D: diverging views of managers
Authors: Kohtamäki Vuokko
Published: May 2013

Purpose

The purpose of this paper is to examine how the nature of management and leadership is related to the management and development of teaching and R&D (research and development) in higher education institutions.

Design/methodology/approach

The nature of management and leadership is approached by consideration of transformational and transactional leadership styles. The emergence and influence of these two styles in management of teaching and R&D are examined using an electronic questionnaire for senior and middle level managers at Finnish polytechnics.

Findings

Both transactional and transformational environments were identified in polytechnics. Senior and middle level managers did not have the same management and development preferences and their perceptions of the operational and management practices differed. Differences found between the viewpoints of these managers diminished when middle managers perceive transformational environment. In a transactional environment teaching was preferred rather than R&D, the role of personnel and students was less important and the good management practices were less common. In a transformational environment, R&D and integrating teaching and R&D had better circumstances to develop further.

Research limitations/implications

This study is not concerned with how various environmental and contextual factors affect management of teaching and R&D. Nor did this study shed light on the perspectives of teachers on institutional leadership and management.

Practical implications

Development of operations, management and leadership is crucial to integrate and be in transformational interaction involving actors from all levels of a higher education institution. In order to implement changes and improve current practices, managers and leaders should extend the ways they approach and perceive teaching and R&D, their own management and leadership and environment. Personnel training and delegation are both needed.

Originality/value

The paper reports on the findings of an electronic survey distributed to senior and middle managers working in polytechnics in Finland that explores their perceptions of teaching and R&D. This paper provides a topical picture of the operative management of teaching and R&D and its extensive meaning in higher education institutions. In addition, this paper identifies a need to examine practice in Finnish polytechnics in terms of the notion of transformational leadership.
Sustainable leadership: honeybee practices at Thailand's oldest university
Authors: Kantabutra Sooksan , Saratun Molraudee
Published: May 2013

Purpose

The aim of this paper is to adopt Avery and Bergsteiner's 23 sustainable leadership practices derived from sustainable organizations as a framework to examine the leadership practices of Thailand's oldest university.

Design/methodology/approach

Avery and Bergsteiner's principles were grouped into six categories for analysis: long‐term perspective, staff development, organizational culture, innovation, social responsibility, and ethical behavior, providing the framework for analysis of the university. Adopting a multi‐data collection approach, research teams supplemented case study data with participant observations, and reference to documentation and information supplied by, or published about the university. Semi‐structured interviews were held with multiple stakeholders.

Findings

Six core sets of practices consistent with 21 sustainable leadership practices are identified: a focus on a long‐term perspective, staff development, a strong organizational culture, innovation, social and environmental responsibility and ethical behavior.

Practical implications

Since sustainable leadership principles link to enhanced brand and reputation, customer and staff satisfaction, and financial performance, the Sustainable Leadership Grid provides educational leaders with a useful checklist for this purpose.

Originality/value

This paper contains the first examination of sustainable leadership in the higher education sector. It shows that even a public service organization can adopt the long‐term, socially responsible principles of sustainable leadership.