bluuebunny/crossref_metadata_2025 huggingface dataset:
The energy of naturally curved elastic rods with an application to the stretching and contraction of a free helical spring as a model for DNA
Authors: Manning Gerald S.
Published: September 2015

We give a contemporary and direct derivation of a classical, but insufficiently familiar, result in the theory of linear elasticity—a representation for the energy of a stressed elastic rod with central axis that intrinsically takes the shape of a general space curve. We show that the geometric torsion of the space curve, while playing a crucial role in the bending energy, is physically unrelated to the elastic twist. We prove that the twist energy vanishes in the lowest-energy states of a rod subject to constraints that do not restrict the twist. The stretching and contraction energies of a free helical spring are computed. There are local high-energy minima. We show the possibility of using the spring to model the chirality of DNA. We then compare our results with an available atomic level energy simulation that was performed on DNA unconstrained in the same sense as the free spring. We find some possible reflections of springlike behavior in the mechanics of DNA, but, unsurprisingly, the base pairs lend a material substance to the core of DNA that a spring does not capture.
Pressure-induced emergence of unusually high-frequency transverse excitations in a liquid alkali metal: Evidence of two types of collective excitations contributing to the transverse dynamics at high pressures
Authors: Bryk Taras , Ruocco G. , Scopigno T. , Seitsonen Ari P.
Published: September 2015

Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, results in dispersions of longitudinal (L) and transverse (T) collective excitations essentially different from the typical phonon ones. Practically, nothing is known about the effect of high pressure on the dispersion of collective excitations in liquids, which causes strong changes in liquid structure. Here dispersions of L and T collective excitations in liquid Li in the range of pressures up to 186 GPa were studied by ab initio simulations. Two methodologies for dispersion calculations were used: direct estimation from the peak positions of the L/T current spectral functions and simulation-based calculations of wavenumber-dependent collective eigenmodes. It is found that at ambient pressure, the longitudinal and transverse dynamics are well separated, while at high pressures, the transverse current spectral functions, density of vibrational states, and dispersions of collective excitations yield evidence of two types of propagating modes that contribute strongly to transverse dynamics. Emergence of the unusually high-frequency transverse modes gives evidence of the breakdown of a regular viscoelastic theory of transverse dynamics, which is based on coupling of a single transverse propagating mode with shear relaxation. The explanation of the observed high-frequency shift above the viscoelastic value is given by the presence of another branch of collective excitations. With the pressure increasing, coupling between the two types of collective excitations is rationalized within a proposed extended viscoelastic model of transverse dynamics.
The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters
Authors: Meyer Jennifer , Tombers Matthias , van Wüllen Christoph , Niedner-Schatteburg Gereon , Peredkov Sergey , Eberhardt Wolfgang , Neeb Matthias , Palutke Steffen , Martins Michael , Wurth Wilfried
Published: September 2015

We present size dependent spin and orbital magnetic moments of cobalt (Con+, 8 ≤ n ≤ 22), iron (Fen+, 7 ≤ n ≤ 17), and nickel cluster (Nin+, 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results. We discuss the application of scaling laws to the size dependent evolution of the spin and orbital magnetic moments per atom in the clusters. We find a spin scaling law “per cluster diameter,” ∼n−1/3, that interpolates between known atomic and bulk values. In remarkable contrast, the orbital moments do likewise only if the atomic asymptote is exempt. A concept of “primary” and “secondary” (induced) orbital moments is invoked for interpretation.
Diamond-cBN alloy: A universal cutting material
Authors: Wang Pei , He Duanwei , Wang Liping , Kou Zili , Li Yong , Xiong Lun , Hu Qiwei , Xu Chao , Lei Li , Wang Qiming , Liu Jing , Zhao Yusheng
Published: September 2015

Diamond and cubic boron nitride (cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesis and characterization of transparent bulk diamond-cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond-cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. High-speed cutting tests on hardened steel and granite suggest that diamond-cBN alloy is indeed a universal cutting material.
Investigation of narrow-band thermal emission from intersubband transitions in quantum wells
Authors: De Zoysa M. , Asano T. , Inoue T. , Mochizuki K. , Noda S.
Published: September 2015

We investigate thermal emission from n-doped GaAs/AlGaAs quantum wells (QWs). Emission peaks with Lorentzian shapes (linewidth 11∼19 meV) that reflect transitions between the first and second conduction subbands are observed in the mid-infrared range. It is demonstrated that the emission characteristics can be tuned by modifying the QW parameters. The peak emissivity is increased from 0.3 to 0.9 by modifying the doping density, and the peak wavelength is tuned from 6 to 10 μm by changing the well width. The obtained results are useful for the design of narrow-band thermal emitters.
Precise determination of micromotion for trapped-ion optical clocks
Authors: Keller J. , Partner H. L. , Burgermeister T. , Mehlstäubler T. E.
Published: September 2015

As relative systematic frequency uncertainties in trapped-ion spectroscopy are approaching the low 10−18 range, motional frequency shifts account for a considerable fraction of the uncertainty budget. Micromotion, a driven motion fundamentally connected to the principle of the Paul trap, is a particular concern in these systems. In this article, we experimentally investigate at this level three common methods for minimizing and determining the micromotion amplitude. We develop a generalized model for a quantitative application of the photon-correlation technique, which is applicable in the commonly encountered regime where the transition linewidth is comparable to the rf drive frequency. We show that a fractional frequency uncertainty due to the 2nd-order Doppler shift below |Δν/ν|=1×10−20 can be achieved. The quantitative evaluation is verified in an interleaved measurement with the conceptually simpler resolved sideband method. If not performed deep within the Lamb-Dicke regime, a temperature-dependent offset at the level of 10−19 is observed in resolved sideband measurements due to sampling of intrinsic micromotion. By direct comparison with photon-correlation measurements, we show that the simple to implement parametric heating method is sensitive to micromotion at the level of |Δν/ν|=1×10−20 as well.
Polarization fluctuation behavior of lanthanum substituted Bi4Ti3O12 thin films
Authors: Zhong Ni , Xiang Ping-Hua , Zhang Yuan-Yuan , Wu Xing , Tang Xiao-Dong , Yang Ping-Xiong , Duan Chun-Gang , Chu Jun-Hao
Published: September 2015

Polarization fluctuation behavior of lanthanum substituted Bi4Ti3O12 (Bi4−xLaxTi3O12, BLT) ferroelectric thin films has been examined. Remnant polarization exhibits an initial increase (Pup, 1–106 cycles) and a subsequent decrease (Pdown, 106–109 cycles) with switching cycles, whereas the dielectric constant exhibits a continuous decrease. By careful investigations on the effect of switching frequency and annealing atmosphere on the polarization fluctuation characteristics, we propose that this polarization fluctuation characteristic of BLT films is attributed to the competition between domain pinning and passive layer growing effect, due to the redistribution of oxygen vacancy related defect under external applied field. Pup behavior is dominated by the unpinning of pinned domain, while Pdown behavior is dominated by the reduction of applied field on BLT bulk layer, due to the growing of the passive layer between BLT and Pt electrode. By assuming the dielectric constant and initial thickness of passive layer, the passive layer was estimated to be about 2–5 times thicker than the initial state after 109 cycling.
Surface acoustic wave propagation in graphene film
Authors: Roshchupkin Dmitry , Ortega Luc , Zizak Ivo , Plotitcyna Olga , Matveev Viktor , Kononenko Oleg , Emelin Evgenii , Erko Alexei , Tynyshtykbayev Kurbangali , Irzhak Dmitry , Insepov Zinetula
Published: September 2015

Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.
Experimental comparison of ring and diamond shaped planar Hall effect bridge magnetic field sensors
Authors: Henriksen Anders Dahl , Rizzi Giovanni , Hansen Mikkel Fougt
Published: September 2015

Planar Hall effect magnetic field sensors with ring and diamond shaped geometries are experimentally compared with respect to their magnetic field sensitivity and total signal variation. Theoretically, diamond shaped sensors are predicted to be 41% more sensitive than corresponding ring shaped sensors for negligible shape anisotropy. To experimentally validate this, we have fabricated both sensor geometries in the exchange-biased stack Ni80Fe20(tFM)/Cu(tCu)/Mn80Ir20(10 nm) with tFM=10, 20, and 30 nm and tCu=0, 0.3, and 0.6 nm. Sensors from each stack were characterized by external magnetic field sweeps, which were analyzed in terms of a single domain model. The total signal variation of the diamond sensors was generally found to be about 40% higher than that for the ring sensors in agreement with theoretical predictions. However, for the low-field sensitivity, the corresponding improvement varied from 0% to 35% where the largest improvement was observed for sensor stacks with comparatively strong exchange bias. This is explained by the ring sensors being less affected by shape anisotropy than the diamond sensors. To study the effect of shape anisotropy, we also characterized sensors that were surrounded by the magnetic stack with a small gap of 3 μm. These sensors were found to be less affected by shape anisotropy and thus showed higher low-field sensitivities.
Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers
Authors: Best James P. , Michler Johann , Liu Jianxi , Wang Zhengbang , Tsotsalas Manuel , Maeder Xavier , Röse Silvana , Oberst Vanessa , Liu Jinxuan , Walheim Stefan , Gliemann Hartmut , Weidler Peter G. , Redel Engelbert , Wöll Christof
Published: September 2015

Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (EITO ≈ 96.7 GPa, EHKUST−1 ≈ 22.0 GPa). For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.
Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires
Authors: Chen Wanghua , Pareige Philippe , Castro Celia , Xu Tao , Grandidier Bruno , Stiévenard Didier , Roca i Cabarrocas Pere
Published: September 2015

By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process.
Producing and imaging a thin line of He2∗ molecular tracers in helium-4
Authors: Gao J. , Marakov A. , Guo W. , Pawlowski B. T. , Van Sciver S. W. , Ihas G. G. , McKinsey D. N. , Vinen W. F.
Published: September 2015

Cryogenic helium-4 has long been recognized as a useful material in fluids research. The unique properties of helium-4 in the gaseous phase and the normal liquid phase allow for the generation of turbulent flows with exceptionally high Reynolds and Rayleigh numbers. In the superfluid phase, helium-4 exhibits two-fluid hydrodynamics and possesses fascinating properties due to its quantum nature. However, studying the flows in helium-4 has been very challenging largely due to the lack of effective visualization and velocimetry techniques. In this article, we discuss the development of novel instrumentation for flow-visualization in helium based on the generation and imaging of thin lines of metastable He2∗ tracer molecules. These molecular tracers are created via femtosecond-laser field-ionization of helium atoms and can be imaged using a laser-induced fluorescence technique. By observing the displacement and distortion of the tracer lines in helium, quantitative information about the flow field can be extracted. We present experimental results in the study of thermal counterflow in superfluid helium that validate the concept of this technique. We also discuss anticipated future developments of this powerful visualization technique.
Transition metal decorated graphene-like zinc oxide monolayer: A first-principles investigation
Authors: Lei Jie , Xu Ming-Chun , Hu Shu-Jun
Published: September 2015

Transition metal (TM) atoms have been extensively employed to decorate the two-dimensional materials, endowing them with promising physical properties. Here, we have studied the adsorption of TM atoms (V, Cr, Mn, Fe, and Co) on graphene-like zinc oxide monolayer (g-ZnO) and the substitution of Zn by TM using first-principles calculations to search for the most likely configurations when TM atoms are deposited on g-ZnO. We found that when a V atom is initially placed on the top of Zn atom, V will squeeze out Zn from the two-dimensional plane then substitute it, which is a no barrier substitution process. For heavier elements (Cr to Co), although the substitution configurations are more stable than the adsorption ones, there is an energy barrier for the adsorption-substitution transition with the height of tens to hundreds meV. Therefore, Cr to Co prefers to be adsorbed on the hollow site or the top of oxygen, which is further verified by the molecular dynamics simulations. The decoration of TM is revealed to be a promising approach in terms of tuning the work function of g-ZnO in a large energy range.
Gas heating effects on the formation and propagation of a microwave streamer in air
Authors: Kourtzanidis Konstantinos , Rogier François , Boeuf Jean-Pierre
Published: September 2015

The development of microwave plasma streamers at 110 GHz in atmospheric pressure air is numerically investigated taking into account the intense gas heating and its effects on the plasma formation and dynamics. The simulations are based on an implicit finite difference time domain formulation of Maxwell's equations coupled with a simple plasma fluid model and a real gas Euler equation solver. The numerical results show how the formation of a shock wave due to the large microwave power absorbed by the plasma and converted into gas heating strongly modifies the streamer elongation and dynamics. A microwave streamer filament stretches along its axis because of ionization-diffusion mechanisms in the enhanced electric field at the streamer tips. The change in the gas density distribution associated with the formation of shock wave due to gas heating strongly modifies the ionization and diffusion mechanisms and tends to limit the on-axis microwave streamer elongation by enhancing resonance effects. The simulations suggest that gas heating effects also play an important role in the observed bending or branching of microwave streamers after they have reached a critical length.
Fluctuation-dissipation theorem and 1/f noise of bulk acoustic wave cavities
Authors: Sthal F. , Devel M. , Imbaud J. , Bourquin R. , Cibiel G.
Published: September 2015

The short time stability in quartz crystal ultra-stable oscillators is limited by some intrinsic frequency fluctuations with a 1/f power spectral density. The physical origin of this 1/f noise is still unknown. In this paper, the fluctuation dissipation theorem is used to numerically evaluate the importance of the contribution of internal damping of thickness fluctuations on the level of noise for bulk acoustic wave cavities. A 1/f contribution to the power spectral density of frequency noise for the shear mode usually used is obtained. Its study provides a possible explanation for the fact that, for the best resonators, the 1/f noise amplitude is usually disconnected from the quality factor measured at resonance.
Rapid characterization of microscopic two-level systems using Landau-Zener transitions in a superconducting qubit
Authors: Tan Xinsheng , Yu Haifeng , Yu Yang , Han Siyuan
Published: September 2015

We demonstrate a fast method to detect microscopic two-level systems in a superconducting phase qubit. By monitoring the population leak after sweeping the qubit bias flux, we are able to measure the two-level systems that are coupled with the qubit. Compared with the traditional method that detects two-level systems by energy spectroscopy, our method is faster and more sensitive. This method supplies a useful tool to investigate two-level systems in solid-state qubits.
Influences of porous reservoir Laplace pressure on emissions from passively fed ionic liquid electrospray sources
Authors: Courtney Daniel G. , Shea Herbert
Published: September 2015

Passively fed ionic liquid electrospray sources are capable of efficiently emitting a variety of ion beams with promising applications to spacecraft propulsion and as focused ion beams. Practical devices will require integrated or coupled ionic liquid reservoirs; the effects of which have not been explored in detail. Porous reservoirs are a simple, scalable solution. However, we have shown that their pore size can dramatically alter the beam composition. Emitting the ionic liquid 1-ethyl-3-methylimidazolium bis(triflouromethylsulfonyl)amide, the same device was shown to yield either an ion or droplet dominated beam when using reservoirs of small or large pore size, respectively; with the latter having a mass flow in excess of 15 times larger than the former at negative polarity. Another source, emitting nearly purely ionic beams of 1-ethyl-3-methylimidazolium tetrafluoroborate, was similarly shown to emit a significant droplet population when coupled to reservoirs of large (>100 μm) pores; constituting a reduction in propulsive efficiency from greater than 70% to less than 30%. Furthermore, we show that reservoir selection can alter the voltage required to obtain and sustain emission, increasing with smaller pore size.
Interference effect on optical signals of monolayer MoS2
Authors: Zhang Hui , Wan Yi , Ma Yaoguang , Wang Wei , Wang Yilun , Dai Lun
Published: September 2015

Both Raman spectroscopy and the photoluminescence (PL) spectroscopy are intensively used in studying the characteristics of monolayer MoS2. However, the substrate-related interference effect will influence the optical signal intensities collected from monolayer MoS2. In this work, we investigated the influence of multilayer film interference on the optical signal intensity of monolayer MoS2 on SiO2/Si substrate. Based on our results, the most commonly used substrate for monolayer MoS2, SiO2/Si with SiO2 thickness around 280–300 nm, is not the optimized choice. By considering the interference effect caused by the Air-MoS2-SiO2 multilayers, we can now enhance the optical signal intensity of monolayer MoS2 greatly by selecting proper SiO2 thickness for any chosen incident light wavelength.
Note: Utilization of polymer gel as a bolus compensator and a dosimeter in the near-surface buildup region for breast-conserving therapy
Authors: Fuse Hiraku , Shinoda Kazuya , Inohira Masaya , Kawamura Hiraku , Miyamoto Katsumi , Sakae Takeji , Fujisaki Tatsuya
Published: September 2015

Tangential beam radiotherapy is routinely used for radiation therapy after breast conserving surgery. A tissue-equivalent bolus placed on the irradiated area shifts the depth of the dose distribution; this bolus provides uniform dose distribution to the breast. The gel bolus made by the BANG-Pro® polymer gel and in an oxygen non-transmission pack was applicable as a dosimeter to measure dose distribution in near-surface buildup region. We validated the use of the gel bolus to improve in the whole-breast/chest wall, including the near-surface buildup region.
Characteristics in the jet region of helium radio-frequency atmospheric-pressure glow discharge with array generators
Authors: Wang Zhi-Bin , Nie Qiu-Yue
Published: September 2015

The two-dimensional spatially extended atmospheric plasma arrays by many parallel radio-frequency glow discharge plasma jets packed densely, represent a feature option of large-scale low-temperature atmospheric plasma technologies with distinct capability of directed delivery of reactive species and good insusceptibility to sample variations. However, it is still a challenge to form plasma jet with large area of uniform active species on a downstream substrate due to the complex interactions between individual jets. This paper proposes to numerically study the strategy and mechanism of control/modulation for the array discharge to produce two-dimensional plasma uniformity in the downstream working area. In this work, a two dimensional fluid model is employed to investigate the characteristics in the jet region of helium radio-frequency atmospheric-pressure glow discharge (RF APGD) with array generators. The influences of upstream discharge characteristics, gas flow and their cooperative effects on the distribution of species densities, gas temperatures and the uniformity of active species in the material treating area is studied, and the essential strategy for the modulation method is acquired. The results will be significant for deep understanding of coupling behaviors of multiple plasma plumes in the RF APGD array and applications of the technology.
Ferroelectric, and piezoelectric properties of BaTi1−xAlxO3, 0 ≤ x ≤ 0.015
Authors: Ali Ahmed I. , Hassen A. , Khang Nguyen Cao , Kim Y. S.
Published: September 2015

Single phase polycrystalline samples of BaTi1−xAlxO3, 0 ≤ x ≤ 0.015, have been prepared by a conventional powder processing method. The Rietveld refinements of X- ray powder diffraction patterns at room temperature indicate that the samples crystallize in tetragonal structure with group symmetry P4mm. Because of the oxygen vacancies, the volume of the unit cell increases with increasing x. Field emission scanning electron microscopy revealed that the particle size of pure BTO ceramics was affected by the Al content. Dielectric, ferroelectric and piezoelectric properties of pure BTO as well as Al-doped BTO were studied. It was found that the dielectric permittivity (ε′) increases significantly with increasing x while the transition from ferroelectric phase to a paraelectric phase changes slightly. The Curie-Weiss law is verified over a wide temperature range. Both ferroelectric and piezoelectric properties of BTO are enhanced by the substitution of Ti4+ by Al3+ ions. Piezoelectric strains of Al-doped BTO showed a suitable behavior for application compared with that of pure BTO compound. Finally, the results obtained in this work are discussed and compared with those for similar materials.
Brønsted Acid-Mediated Radical Processes in Organic Synthesis
Authors: Nicholls Thomas P. , Henderson Luke C. , Bissember Alex C.
Published: September 2015

This highlight focuses on recent applications of Brønsted acid-mediated radical processes across a range of reaction manifolds, including transition metal-based catalysis, photochemistry, and polymer science. A brief overview of significant research developments in the area and a discussion of the key mechanistic features of notable transformations are provided.
Effect of docosahexanoic acid on quality of frozen–thawed bull semen in BioXcell extender
Authors: Kaka Asmatullah , Haron Wahid , Yusoff Rosnina , Yimer Nurhusien , Khumran A. M. , Sarsaifi Kazhal , Behan Atique Ahmed , Kaka Ubedullah , Memon Akeel Ahmed , Ebrahimi Mahdi
Published: September 2015

This study was conducted to investigate the effect of docosahexanoic acid (DHA) supplementation in BioXcell extender on the quality of frozen–thawed bull semen. Twenty-four ejaculates were collected from three bulls (eight from each bull). Ejaculates with motility ≥70% and normal morphology ≥80% were extended into BioXcell extender to which 0 (control), 3, 5, 10 or 15 ng mL–1 DHA was added. The supplemented semen samples were incubated at 37°C for 15 min for DHA uptake by spermatozoa. Later, samples were cooled for 2 h at 5°C and packaged into 0.25-mL straws, frozen in liquid nitrogen for 24 h and subsequently thawed for evaluation. Results are presented as percentages ± s.e.m. Supplementation with DHA at 3 ng mL–1 significantly improved sperm functional parameters including sperm motility, normal morphology, viability, acrosome integrity and membrane integrity when compared with other supplemented groups and the control. Lipid peroxidation increased as the incorporation of DHA supplementation increased. In conclusion, 3 ng mL–1 concentration of DHA resulted in superior quality of frozen–thawed bull spermatozoa and is suggested as the optimum level of DHA to be added into BioXcell extender.
Kinetochore function is controlled by a phospho-dependent coexpansion of inner and outer components
Authors: Wynne David J. , Funabiki Hironori
Published: September 2015

It is widely accepted that the kinetochore is built on CENP-A–marked centromeric chromatin in a hierarchical order from inner to outer kinetochore. Recruitment of many kinetochore proteins depends on microtubule attachment status, but it remains unclear how their assembly/disassembly is orchestrated. Applying 3D structured illumination microscopy to Xenopus laevis egg extracts, here we reveal that in the absence of microtubule attachment, proteins responsible for lateral attachment and spindle checkpoint signaling expand to form micrometer-scale fibrous structures over CENP-A–free chromatin, whereas a core module responsible for end-on attachment (CENP-A, CENP-T, and Ndc80) does not. Both outer kinetochore proteins (Bub1, BubR1, Mad1, and CENP-E) and the inner kinetochore component CENP-C are integral components of the expandable module, whose assembly depends on multiple mitotic kinases (Aurora B, Mps1, and Plx1) and is suppressed by protein phosphatase 1. We propose that phospho-dependent coexpansion of CENP-C and outer kinetochore proteins promotes checkpoint signal amplification and lateral attachment, whereas their selective disassembly enables the transition to end-on attachment.
The fusogenic lipid phosphatidic acid promotes the biogenesis of mitochondrial outer membrane protein Ugo1
Authors: Vögtle F.-Nora , Keller Michael , Taskin Asli A. , Horvath Susanne E. , Guan Xue Li , Prinz Claudia , Opalińska Magdalena , Zorzin Carina , van der Laan Martin , Wenk Markus R. , Schubert Rolf , Wiedemann Nils , Holzer Martin , Meisinger Chris
Published: September 2015

Import and assembly of mitochondrial proteins depend on a complex interplay of proteinaceous translocation machineries. The role of lipids in this process has been studied only marginally and so far no direct role for a specific lipid in mitochondrial protein biogenesis has been shown. Here we analyzed a potential role of phosphatidic acid (PA) in biogenesis of mitochondrial proteins in Saccharomyces cerevisiae. In vivo remodeling of the mitochondrial lipid composition by lithocholic acid treatment or by ablation of the lipid transport protein Ups1, both leading to an increase of mitochondrial PA levels, specifically stimulated the biogenesis of the outer membrane protein Ugo1, a component of the mitochondrial fusion machinery. We reconstituted the import and assembly pathway of Ugo1 in protein-free liposomes, mimicking the outer membrane phospholipid composition, and found a direct dependency of Ugo1 biogenesis on PA. Thus, PA represents the first lipid that is directly involved in the biogenesis pathway of a mitochondrial membrane protein.
Kinetochores expand their reach
Authors: Short Ben
Published: September 2015

Kinetochore proteins form extended filaments that could promote checkpoint activation and microtubule capture.
Light-emitting diode street lights reduce last-ditch evasive manoeuvres by moths to bat echolocation calls
Authors: Wakefield Andrew , Stone Emma L. , Jones Gareth , Harris Stephen
Published: September 2015

The light-emitting diode (LED) street light market is expanding globally, and it is important to understand how LED lights affect wildlife populations. We compared evasive flight responses of moths to bat echolocation calls experimentally under LED-lit and -unlit conditions. Significantly, fewer moths performed ‘powerdive’ flight manoeuvres in response to bat calls (feeding buzz sequences fromNyctalusspp.) under an LED street light than in the dark. LED street lights reduce the anti-predator behaviour of moths, shifting the balance in favour of their predators, aerial hawking bats.
High effectiveness of tailored flower strips in reducing pests and crop plant damage
Authors: Tschumi Matthias , Albrecht Matthias , Entling Martin H. , Jacot Katja
Published: September 2015

Providing key resources to animals may enhance both their biodiversity and the ecosystem services they provide. We examined the performance of annual flower strips targeted at the promotion of natural pest control in winter wheat. Flower strips were experimentally sown along 10 winter wheat fields across a gradient of landscape complexity (i.e. proportion non-crop area within 750 m around focal fields) and compared with 15 fields with wheat control strips. We found strong reductions in cereal leaf beetle (CLB) density (larvae: 40%; adults of the second generation: 53%) and plant damage caused by CLB (61%) in fields with flower strips compared with control fields. Natural enemies of CLB were strongly increased in flower strips and in part also in adjacent wheat fields. Flower strip effects on natural enemies, pests and crop damage were largely independent of landscape complexity (8–75% non-crop area). Our study demonstrates a high effectiveness of annual flower strips in promoting pest control, reducing CLB pest levels below the economic threshold. Hence, the studied flower strip offers a viable alternative to insecticides. This highlights the high potential of tailored agri-environment schemes to contribute to ecological intensification and may encourage more farmers to adopt such schemes.
Is ice-rafted sediment in a North Pole marine record evidence for perennial sea-ice cover?
Authors: Tremblay L. B. , Schmidt G. A. , Pfirman S. , Newton R. , DeRepentigny P.
Published: September 2015

Ice-rafted sediments of Eurasian and North American origin are found consistently in the upper part (13 Ma BP to present) of the Arctic Coring Expedition (ACEX) ocean core from the Lomonosov Ridge, near the North Pole (≈88° N). Based on modern sea-ice drift trajectories and speeds, this has been taken as evidence of the presence of a perennial sea-ice cover in the Arctic Ocean from the middle Miocene onwards (Krylov
et al.
2008
Paleoceanography
23, PA1S06. (
doi:10.1029/2007PA001497
); Darby 2008
Paleoceanography
23, PA1S07. (
doi:10.1029/2007PA001479
)). However, other high latitude land and marine records indicate a long-term trend towards cooling broken by periods of extensive warming suggestive of a seasonally ice-free Arctic between the Miocene and the present (Polyak
et al.
2010
Quaternary Science Reviews
29, 1757–1778. (
doi:10.1016/j.quascirev.2010.02.010
)). We use a coupled sea-ice slab-ocean model including sediment transport tracers to map the spatial distribution of ice-rafted deposits in the Arctic Ocean. We use 6 hourly wind forcing and surface heat fluxes for two different climates: one with a perennial sea-ice cover similar to that of the present day and one with seasonally ice-free conditions, similar to that simulated in future projections. Model results confirm that in the present-day climate, sea ice takes more than 1 year to transport sediment from all its peripheral seas to the North Pole. However, in a warmer climate, sea-ice speeds are significantly faster (for the same wind forcing) and can deposit sediments of Laptev, East Siberian and perhaps also Beaufort Sea origin at the North Pole. This is primarily because of the fact that sea-ice interactions are much weaker with a thinner ice cover and there is less resistance to drift. We conclude that the presence of ice-rafted sediment of Eurasian and North American origin at the North Pole does not imply a perennial sea-ice cover in the Arctic Ocean, reconciling the ACEX ocean core data with other land and marine records.
Factors affecting the psychological distress among unemployed and re-employed individuals
Authors: Tuncay Tarik , Yildirim Bugra
Published: September 2015

Purpose

– The purpose of this paper is to examine coping strategies, social support, and psychological distress for comparable samples of unemployed (n=389) and re-employed (n=270) individuals. The authors hypothesized that problem-focused coping and higher levels of social support would be associated with lower levels of psychological distress for unemployed vs re-employed participants.

Design/methodology/approach

– The cross-sectional design and the convenience sampling method were used in the study.

Findings

– Although unemployed participants reported poorer coping, higher levels of psychological distress, and lower levels of social support compared to re-employed participants; social support and coping strategies predicted psychological distress. Multiple regression analyses suggest that emotion-focused coping strategies were related to higher levels of psychological distress, whereas social support and problem-focused coping strategies were related to lower levels of psychological distress. Social support accounted for more variance in participants’ psychological distress above and beyond all other variables. Single and unemployed participants of the study used less problem-focused, more emotion-focused coping, and perceived lower social support than married unemployed. Gender and marital status of the unemployed were also significantly associated with psychological distress. In addition, older and less educated unemployed participants perceived less social support and used emotion-focused coping more frequently.

Practical implications

– The findings indicated that being female, single, older, and low educated are the potential sociodemographic risk factors for the psychosocial well-being of unemployed people.

Originality/value

– The favourable effects of certain coping strategies suggest the potential benefits of interventions to reduce reliance on emotion-focused coping and stimulate more problem-focused strategies in order to enhance psychological well-being.
Proactivity in career development of employees
Authors: Presbitero Alfred
Published: September 2015

Purpose

– Drawing on proactivity literature, the purpose of this paper is to investigate the relationship between employee’s proactive career planning (taking initiative to prepare for one’s career) and proactive career enacting (taking initiative to act on career plans). This study also looks into the influence of proactive personality and cognitive complexity in the relationship between proactive career planning and proactive career enacting.

Design/methodology/approach

– Survey data were collected in Australia (study 1;n=271) and were tested using structural equation modeling. Another set of survey data were collected in a different cultural context in the Philippines (study 2;n=215) for cross-cultural validation.

Findings

– Results show that proactive career planning and proactive career enacting are positively and significantly related in both cultural contexts. Results also show that proactive personality or the stable disposition of an individual to take initiative and be involved in future-oriented actions plays a significant role in moderating the relationship between proactive career planning and proactive career enacting. In addition, results show that cognitive complexity which pertains to an individual’s capacity to construe social behaviors in multidimensional ways moderates the relationship between proactive career planning and proactive career enacting.

Practical implications

– In today’s turbulent environment, employees need to be proactive when developing their careers. This study highlights the importance of being proactive when managing one’s career. Employees’ proactive personality and cognitive complexity also help in strengthening the link between proactive career planning and proactive career enacting, hence, these individual-level characteristics need to be developed and enhanced in organizations.

Originality/value

– This study is valuable as it extends and advances the understanding on how proactivity (proactive career planning, proactive career enacting, proactive personality) and cognitive complexity can contribute to career development of employees.
Psychological need fulfillment as a mediator of the relationship between transformational leadership and positive job attitudes
Authors: Hetland Jørn , Hetland Hilde , Bakker Arnold B. , Demerouti Evangelia , Andreassen Cecilie S. , Pallesen Ståle
Published: September 2015

Purpose

– The purpose of this paper is to explore the possible mediating role of need fulfilment in the relationship between transformational leadership and employee job attitudes (job satisfaction and dedication).

Design/methodology/approach

– The two samples include both cross-sectional and diary data. The cross-sectional sample (sample 1) consisted of 661 employees from various organizations. In the diary study (sample 2), 65 employees completed a daily questionnaire on five consecutive working days, yielding 325 measurement points in total. The authors analyzed the data using structural equation modeling (Mplus 5) and multilevel analyses (MLwiN 2.20).

Findings

– As hypothesized, support for full mediation of the relationship between transformational leadership and positive job attitudes through the fulfilment of psychological needs were found both on a general level and on a daily basis.

Originality/value

– The paper is based on a multi study approach and empirically addresses the link between transformational leadership and positive job attitudes, and the role of basic need fulfilment in this relationship on both a general and daily level.
Employability skills of international accounting graduates
Authors: Jackling Beverley , Natoli Riccardo
Published: September 2015

Purpose

– The purpose of this paper is to report on the perceptions of internship providers with respect to the employability skills of international accounting graduates that undertake a Professional Year Program (PYP) incorporating a 12-week (240 hour) internship.

Design/methodology/approach

– The study involved a survey of internship providers that required open and closed responses addressing perceptions of the skill of interns and rating of satisfaction with the PYP program as an employment preparation program.

Findings

– The results indicate that from the internship providers’ perspective the most highly developed skill of interns is team skills. However, over 40 percent of respondents indicated that interns had failed to demonstrate the capacity to be “work ready” with respect to business acculturation, capacity to handle unfamiliar problems and communication skills. One-third of respondents had ongoing concerns with the PYP as a means of preparing Australian educated international graduates for work in the accounting profession.

Practical implications

– There was evidence of a need for a more cohesive theoretical underpinning of the internship program as a means of enhancing the transition from study to work.

Originality/value

– This study was the first independent study to examine perceptions of a PYP incorporating an internship program to enhance the employability of international accounting graduates who seek professional recognition in Australia. The study provides insights of internship providers of the employability skills of international graduates. The results are timely given the emergence of the demand for relevant work experience enabling international students to enhance their employability globally.
The effects of empathy and listening of salespeople on relationship quality in the retail banking industry
Authors: Itani Omar S. , Inyang Aniefre Eddie
Published: September 2015

Purpose

– The purpose of this paper is to examine the relations between salespeople’s empathy and listening behaviour and the relationship quality (RQ) customers have with their banks, taking into consideration the moderating effect of felt stress (FS) experienced by salespeople. The paper examines specific effects of FS on factors related to a salesperson’s performance.

Design/methodology/approach

– To examine the proposed model, responses from 150 customers were collected and matched with responses from 25 salespeople working at a major ba ' nk in Chile. The paper analysed the dyadic data gathered using two analysis techniques. Structural equation modelling was employed to test the relationships proposed at the customer level. Moreover, hierarchical linear modelling was used to test the moderating effect of FS, measured at the salesperson level, on the proposed relationships.

Findings

– The results show that customers’ perceptions of salespeople’s listening behaviour mediate the relationship between customers’ perception of salespeople’s empathy and RQ with the bank. Moreover, the positive relationship between salespeople’s empathy and salespeople’s listening behaviour, and the positive relationship between salesperson’s listening and customer’s RQ with bank are attenuated by the salesperson’s FS.

Originality/value

– This paper examined the effects of the salesperson’s empathy and listening behaviour on the quality of customer relationships with the bank. Moreover, dyadic data show that such effects are influenced by variables related to the bank’s salespeople, such as FS. The findings show that under high FS conditions, salespeople with high listening skills will have negative effects on their customers’ RQ with the bank.
A study of mobile banking usage in Iran
Authors: Mohammadi Hossein
Published: September 2015

Purpose

– The purpose of this paper is to explore barriers, the mediating role of usability and the moderating effects of self-efficacy and perceived image on consumers’ attitudes toward use of mobile banking (MB) in Iran.

Design/methodology/approach

– Based on the consumer data collected through a survey, structural equations modeling and path analysis were employed to test the research model.

Findings

– The results revealed that “system compatibility” was found to be the main factor affecting users’ attitudes toward use of MB. “Resistance” showed a significant negative effect on both ease of use and usefulness. “Perceived usefulness” mediated the relationship between ease of use and users’ attitudes. At last, contrary to self-efficacy which showed no significant effect, perceived image moderated the relationships between usefulness and attitude.

Research limitations/implications

– The sample was only composed of MB users and non-users were not studied.

Originality/value

– Past studies have seldom examined the role of individual drivers like self-efficacy and social drivers like perceived image as moderating variables in the context of developing countries.