bluuebunny/crossref_metadata_2025 huggingface dataset:
Giant quasiparticle bandgap modulation in graphene nanoribbons supported on weakly interacting surfaces
Authors: Jiang Xueping , Kharche Neerav , Kohl Paul , Boykin Timothy B. , Klimeck Gerhard , Luisier Mathieu , Ajayan Pulickel M. , Nayak Saroj K.
Published: September 2013

In general, there are two major factors affecting bandgaps in nanostructures: (i) the enhanced electron-electron interactions due to confinement and (ii) the modified self-energy of electrons due to the dielectric screening. While recent theoretical studies on graphene nanoribbons (GNRs) report on the first effect, the effect of dielectric screening from the surrounding materials such as substrates has not been thoroughly investigated. Using large-scale electronic structure calculations based on the GW approach, we show that when GNRs are deposited on substrates, bandgaps get strongly suppressed (by as much as 1 eV) even though the GNR-substrate interaction is weak.
Charge and spin Hall effect in spin chiral ferromagnetic graphene
Authors: Zare Rameshti Babak , Zareyan Malek
Published: September 2013

We predict a specific type of charge Hall effect in undoped ferromagnetic graphene that is generated by the spin Hall mechanism in the absence of an external magnetic field. The essential feature is the so-called spin chiral configuration of the spin subbands in such a magnetic material where carriers with opposite spin direction are of different type of electron-like or hole-like. Within the semiclassical theory of spin-orbital dynamics of electrons, we obtain that a longitudinal electric field can produce a spin-orbit transverse current of pure charge with no polarization of the spin and the valley.
Exact kinetic theory for the instability of an electron beam in a hot magnetized plasma
Authors: Timofeev I. V. , Annenkov V. V.
Published: September 2013

Efficiency of collective beam-plasma interaction strongly depends on the growth rates of dominant instabilities excited in the system. Nevertheless, exact calculations of the full unstable spectrum in the framework of relativistic kinetic theory for arbitrary magnetic fields and particle distributions were unknown until now. In this paper, we give an example of such a calculation answering the question whether the finite thermal spreads of plasma electrons are able to suppress the fastest growing modes in the beam-plasma system. It is shown that nonrelativistic temperatures of Maxwellian plasmas can stabilize only the oblique instabilities of relativistic beam. On the contrary, non-Maxwellian tails typically found in laboratory beam-plasma experiments are able to substantially reduce the growth rate of the dominant longitudinal modes affecting the efficiency of turbulent plasma heating.
Sensitivity analysis of single-layer graphene resonators using atomic finite element method
Authors: Lee Haw-Long , Hsu Jung-Chang , Lin Shu-Yu , Chang Win-Jin
Published: September 2013

Atomic finite element simulation is applied to study the natural frequency and sensitivity of a single-layer graphene-based resonator with CCCC, SSSS, CFCF, SFSF, and CFCF boundary conditions using the commercial code ANSYS. The fundamental frequencies of the graphene sheet are compared with the results of the previous finite element study. In addition, the sensitivity of the resonator is compared with the early work based on nonlocal elasticity theory. The results of the comparison are very good in all considered cases. The sensitivities of the resonator with different boundary conditions are obtained, and the order based on the boundary condition is CCCC > SSSS > CFCF > SFSF > CFFF. The highest sensitivity is obtained when the attached mass is located at the center of the resonator. This is useful for the design of a highly sensitive graphene-based mass sensor.
Prolonged reorganization of thiol-capped Au nanoparticles layered structures
Authors: Kundu Sarathi , Das Kaushik , Konovalov Oleg
Published: September 2013

Prolonged reorganization behaviour of mono-, di-, tri- and multi-layer films of Au nanoparticles prepared by Langmuir-Blodgett method on hydrophobic Si(001) substrates have been studied by using X-ray scattering techniques. Out-of-plane study shows that although at the initial stage the reorganization occurs through the compaction of the films keeping the layered structure unchanged but finally all layered structures modify to monolayer structure. Due to this reorganization the Au density increases within the nanometer thick films. In-plane study shows that inside the reorganized films Au nanoparticles are distributed randomly and the particle size modifies as the metallic core of Au nanoparticles coalesces.
Photoionization Mass Spectrometric and Kinetic Modeling of Low-pressure Pyrolysis of Benzene
Authors: Yang Jiu-zhong , Zhao Long , Cai Jiang-huai , Qi Fei , Li Yu-yang
Published: September 2013

Pyrolysis of benzene at 30 Torr was studied from 1360 K to 1820 K in this work. Synchrotron vacuum ultraviolet photoionization mass spectrometry was employed to detect the pyrolysis products such as radicals, isomers and polycyclic aromatic hydrocarbons, and measure their mole fraction profiles versus temperature. A low-pressure pyrolysis model of benzene was developed and validated by the experimental results. Rate of production analysis was performed to reveal the major reaction networks in both fuel decomposition and aromatic growth processes. It is concluded that benzene is mainly decomposed via H-abstraction reaction to produce phenyl and partly decomposed via unimolecular decomposition reactions to produce propargyl or phenyl. The decomposition process stops at the formation of acetylene and polyyne species like diacetylene and 1,3,5-hexatriyne due to their high thermal stabilities. Besides, the aromatic growth process in the low-pressure pyrolysis of benzene is concluded to initiate from benzene and phenyl, and is controlled by the even carbon growth mechanism due to the inhibited formation of C5 and C7 species which play important roles in the odd carbon growth mechanism.
Resonance-Enhanced Photon Excitation Spectroscopy of the Even-Parity 3p5(2P1/2)nl′ [K′]J (l′=1, 3) Autoionizing Rydberg States of Ar
Authors: Li Chun-yan , He Zhi-wei , Wang Ting-ting , Zhen Jun-feng , Chen Yang , Zhang Jin-song
Published: September 2013

Metastable 40Ar* atoms are produced in the two metastable states 3p54s [3/2]2 and 3p54s′ [1/2]0 in a pulsed DC discharge in a beam, and are subsequently excited to the even-parity autoionizing resonance series 3p5np′ [3/2]1,2, 3p5np′ [1/2]1, and 3p5nf′ [5/2]3 using single photon excitation with a pulsed dye laser. The excitation spectra of the even-parity autoionizing resonance series from the metastable 40Ar* are obtained by recording the autoionized Ar+ ions with time-of-flight ion detection in the photon energy range of 32500–35600 cm−1 with an experimental bandwidth of <0.1 cm−1. A wealth of autoionizing resonances are newly observed, from which more precise and systematic spectroscopic data of the level energies and quantum defects are derived.
Investigation on Non-covalent Complexes of Cyclodextrins with Li+ in Gas Phase by Mass Spectrometry
Authors: He Xiao-dan , Wei Wang-hui , Chu Yan-qiu , Liu Zhi-pan , Ding Chuan-fan
Published: September 2013

To investigate the non-covalent interaction between cyclodextrins (CD) and lithium ion, a stoichiometry of α-CD, β-CD, heptakis(2,6-di-O-methyl)-β-CD (DM-β-CD), or heptakis(2,3,6-tri-O-methyl)-β-CD (TM-β-CD) was mixed with lithium salt, respectively, and then incubated at room temperature for 10 min to reach the equilibrium. In positive mode, the electrospray ionization mass spectrometry (ESI-MS) results demonstrated that lithium ion can conjugate to α-, β-, DM-β- or TM-β-CD and form 1:1 stoichiometric non-covalent complexes. The binding of the complexes was further confirmed by collision-induced dissociation. The dissociation constants Kd1 of four complexes (Li+α-CD, Li+β- CD, Li+DM-β-CD, and Li+TM-β-CD) were determined by mass spectrometric titration. The results showed Kd1 were 18.7, 26.7, 33.6, 30.5 μmol/L for the complexes of Li+ with α-CD, β-CD, DM-β-CD, and TM-β-CD, respectively. Kd1 for the Li+ complexes of β-CD is smaller than that of DM-β-CD due to its steric effect of the partial substituted -CH3. The Kd1 for the Li+ complexes of DM-β-CD is nearly in agreement with that of TM-β-CD, indicating Li+ is more likely to locate in the small rim of DM-β-CD's hydrophobic cavity. The DFT results showed through electrostatic interaction, one Li+ can strongly conjugate to four neighboring oxygen atoms. For the (α-CD+Li)+ complex, one Li+ may also situate the small rim of α-CD's hydrophobic cavity to form a non-specific host-guest complex.
A Revisit to the Role of Bridge-adsorbed Formate in the Electrocatalytic Oxidation of Formic Acid at Pt Electrodes
Authors: Xu Jie , Mei Dong , Yuan Dao-fu , Zhang Zun-biao , Liu Shao-xiong , Chen Yan-xia
Published: September 2013

The mechanism and kinetics of electrocatalytic oxidation of formic acid at Pt electrodes is discussed in detail based on previous electrochemical in-situ ATR-FTIRS data [Langmuir 22, 10399 (2006) and Angewa. Chem. Int. Ed. 50, 1159 (2011)]. A kinetic model with formic acid adsorption (and probably the simultaneous CH bond activation) as the rate determining step, which contributes to the majority of reaction current for formic acid oxidation, was proposed for the direct pathway. The model simulates well the IR spectroscopic results obtained under conditions where the poisoning effect of carbon monoxide (CO) is negligible and formic acid concentration is below 0.1 mol/L. The kinetic simulation predicts that in the direct pathway formic acid oxidation probably only needs one Pt atom as active site, formate is the site blocking species instead of being the active intermediate. We review in detail the conclusion that formate pathway (with either 1st or 2nd order reaction kinetics) is the direct pathway, possible origins for the discrepancies are pointed out.
Detailed Temperature-dependent Study of n-Heptane Pyrolysis at High Temperature
Authors: Ding Jun-xia , He Guo-zhong , Zhang Liang
Published: September 2013

n-Heptane is the most important straight chain paraffin in the fossil-fuel industry. In this work, pyrolysis behavior of n-heptane at high temperature is investigated by a series of ReaxFF based reactive molecular dynamics simulations. Temperature effects on the n-heptane pyrolysis and related products distributions have been detailedly analyzed. The simulation results indicate that the temperature effect is characterized in stages. High temperature can accelerate the decomposition of n-heptane, but the influence becomes small after it reaches a certain level. According to the different reaction behaviors, pyrolysis of n-heptane could be divided into three stages. The variation trends of the mass fraction evolution of ethylene (C2H4), C3, and C4 calculated from reactive molecular dynamics simulations are in good agreement with the previous experimental results. The apparent activation energy extracted from the first-order kinetic analysis is 53.96 kcal/mol and a pre-exponential factor is 55.34×1013 s−1, which is reasonably consistent with the experimental results.
Synthesis and Electrochemical Property of Flowerlike LiFePO4 by Poly(ethylene glycol)-assisted Hydrothermal Process
Authors: Guo Xin , Zhang Yao-cheng , Xiang Hong-fa
Published: September 2013

Flowerlike LiFePO4 particles self-assembled by plate-like crystals with about 200 nm thickness were prepared by the poly(ethylene glycol)-assisted hydrothermal synthesis. Poly(ethylene glycol) in the hydrothermal system played an important role in reducing the thickness of the plate-like LiFePO4 crystals as a co-solvent and forming the flower-like structure as a soft template. The flowerlike LiFePO4 exhibits high discharge capacity of 140 mAh/g and shows quite good cycling performance in the lithium-ion batteries. Considering that the conductive carbon in the obtained LiFePO4 is negligible, the excellent cell performance suggests that the flowerlike LiFePO4 is a promising cathode material for the lithium-ion batteries.
Preparation of BiVO4 Hollow Spheres and its Photocatalytic Degradation of Methylene Blue
Authors: Ma Zhan-ying , Yao Bing-hua
Published: September 2013

Monoclinic BiVO4 hollow nanospheres were successfully prepared via template-free method using citric acid (C6H8O7) as chelating agent and characterized by X-ray diffraction patterns, transmission electron microscope, UV-Vis DRS, and TG-DTA technique. C6H8O7 played an important role in the formation of hollow spheres. Morphology observations revealed that when appropriate amount of C6H8O7 was introduced, the cavity with the diameter of 40 nm was obtained in BiVO4 nanospheres. UV-Vis diffuse reflectance spectra indicated that the samples had absorption in both UV and visible light region. The photocatalytic activities were evaluated by the degradation of methylene blue under Xe lamp irradiation. Hollow spheres endow BiVO4 samples with greatly improved photocatalytic activity. A possible formation mechanism of hollow spheres was proposed.
Preparation of 5-Hydroxymethylfurfural from Cellulose via Fast Depolymerization and Consecutively Catalytic Conversion
Authors: Lai Bin , Zhao Yi , Yan Li-feng
Published: September 2013

The conversion of cellulose to 5-hydroxymethylfurfural (HMF) has been investigated by a one-pot consecutive reaction. At first, cellulose was depolymerised into glucose via a fast degradation of cellulose in molten ZnCl2 in the presence of hydrochloric acid, and the yield of glucose is 75% in 120 s at reaction temperature of 95 °C. Then, DMSO was used as solvent and different kinds of metal chloride were added as catalysts, and the conversion was carried out continuously at 110–130 °C for 0.5–4 h. The yield of HMF was 53% when CrCl3 were used as catalyst. The one-pot two steps conversion was carried out at atmosphere pressure, and it is a simple route to prepare HMF from lignocellulosic feedstock on a large scale.
A Compact Low Energy Electron Microscope for Surface Analysis
Authors: Zhang Guan-hua , Sun Ju-long , Jin Yan-ling , Zang Kan , Guo Fang-zhun , Yang Xue-ming
Published: September 2013

The description and function characterization of a flange-on type low energy electron microscope are given. In this microscope a magnetic beam separator with 10° deflection angle is used in order to facilitate compacting the instrument on a single 10 in. flange. Meanwhile some correcting elements in the electron optical system are simplified to reduce the complexities of construction and operation. The sample is set close to ground potential, so that all the electrostatic lenses are easily to float at high voltages. The performance of the microscope in typical low energy electron microscopy, low energy electron diffraction and photoemission electron microscopy modes is demonstrated through several experiments. A lateral resolution of 51 nm is estimated for low energy electron microscopy imaging. With femtosecond laser as light source, the consequent nonlinear photoemission makes this microscope also suitable for the observation of optical near field phenomena and a lateral resolution of 110 nm is obtained.
Line-profile Analysis of Excitation Spectroscopy in Even 5p5(2P1/2)nl′ [K′]J (l′=1, 3) Autoionizing Resonances of Xe
Authors: Li Chun-yan , Wang Ting-ting , Zhen Jun-feng , Chen Yang , He Zhi-wei
Published: September 2013

The even-parity autoionizing resonance series 5p5np′ [3/2]1, [1/2]1, and 5p5nf′5/2]3 of xenon have been investigated, excited from the two metastable states 5p56s [3/2]2 and 5p56s′ [1/2]0 in the photon energy range of 28000–42000 cm−1 with experimental bandwidth of ̃0.1 cm−1. The excitation spectra of the even-parity autoionizing resonance series show typical asymmetric line shapes. New level energies, quantum defects, line profile indices and resonance widths, resonance lifetimes and reduced widths of the autoionizing resonances are derived by a Fano-type line-shape analysis. The line profile index and the resonance width are shown to be approximately proportional to the effective principal quantum number. The line separation of the 5p5np′ autoionizing resonances is discussed.
Impact of Surface Dipole on Resonant Electron Injection in Scanning Tunneling Spectroscopy
Authors: Wu Qi-hui , Wu Shun-qing , Pakes C. I.
Published: September 2013

Resonant electron injection and first-principles calculations are utilized to study single-adsorbed selenium (Se) atom on a Si(111)-7×7 surface. Theoretical calculations indicate that a negative dipole of 0.61 eV forms toward the adsorbed Se atom due to electron transfer from the associated Si atoms. The formation of surface dipole modifies the effective tunneling barrier height and causes a shift in the energy of the resonant state formed in the vacuum gap between the tip and the sample surface. The experimental data imply that an outward negative surface dipole of 0.61 eV causes a resonant electron injection bias shift to high voltage of about 0.45 V.
Mechanistic Study of Palladium-Catalyzed Oxidative C–H/C–H Coupling of Polyfluoroarenes with Simple Arenes
Authors: Tang Shi-ya , Yu Hai-zhu , You Wan-li , Guo Qing-xiang
Published: September 2013

Pd-catalyzed oxidative C–H/C–H coupling reaction is an emerging type of C–H activation reaction, which attracts great interests because both reaction partners do not require pre-functionalization. In the present study, we employed DFT methods to investigate the mechanism of Pd(OAc)2-catalyzed oxidative C–H/C–H coupling of pentafluorobenzene with benzene. Four possible pathways were examined in the C–H activation part: path A benzene-pentafluorobenzene mechanism (C–H activation of benzene occurs before the C–H activation of pentafluorobenzene), path B pentafluorobenzene-benzene mechanism (C–H activation of benzene occurs after the C–H activation of pentafluorobenzene), path C benzene-pentafluorophenylsilver mechanism (C–H activation of benzene and subsequent transmetalation with pentafluorophenyl silver complex), path D pentafluorophenylsilverbenzene mechanism (transmetalation with pentafluorophenyl silver complex and subsequent C–H activation of benzene). Based on the calculations, the sequences of two C–H activation steps are found to be different in the oxidative couplings of same substrates (i.e. pentafluorobenzene and benzene) in different catalytic systems, where the additive Ag salts played a determinant role. In the absence of Ag salts, the energetically favored pathway is path B (i.e. the C–H activation of pentafluorobenzene takes place before the C–H cleavage of benzene). In contrast, with the aid of Ag salts, the coordination of pentafluorophenylsilver to Pd center could occur easily with a subsequent C–H activation of benzene in the second step, and the second step significantly raises the whole reaction barrier. Alternatively, in the presence of Ag salts, the kinetically preferred mechanism is path C (i.e. the C–H activation of benzene takes place in the first step followed by transmetalation with pentafluorophenylsilver complex), which is similar to path A. The calculations are consistent with the H/D exchange experiment and kinetic isotope effects. Thus the present study not only offers a deeper understanding of oxidative C–H/C–H coupling reaction, but also provides helpful insights to further development of more efficient and selective oxidative C–H/C–H coupling reactions.
Electrochemical Properties of PP13TFSI-LiTFSI-P(VdF-HFP) Ionic Liquid Gel Polymer Electrolytes
Authors: Yang Pei-xia , Liu Lei , Hou Jun , Zhang Jin-qiu
Published: September 2013

N-Methyl-N-propylpiperidiniumbis(trifluoromethanesulfonyl)imide (PP13TFSI), bis(trifluoromethanesulfonyl)imide lithium salt (LiTFSI), and poly(vinylidene difluoride-co-hexafluoropropylene) (P(VdF-HFP)) were mixed and made into ionic liquid gel polymer electrolytes (ILGPEs) by solution casting. The morphology of ILGPEs was observed by scanning electron microscopy. It was found that the ILGPE had a loosened structure with liquid phase uniformly distributed. The ionic conductivity, lithium ion transference number and electrochemical window were measured by electrochemical impedance spectroscopy, chronoamperometric and linear sweep voltammetry. The ionic conductivity and lithium ion transference number of this ILGPE reached 0.79 mS/cm and 0.71 at room temperature, and the electrochemical window was 0 to 5.1 V vs. Li+/Li. Battery tests indicated that the ILGPE is stable when being operated in Li/LiFePO4 batteries. The discharge capacity maintained at about 135, 117, and 100 mAh/g at 30, 75, and 150 mA/g rates, respectively. The capacity retentions were almost 100% after 100 cycles without little capacity fading.
Synthesis of Flower-like NaY(MoO4)2 and Optical Property of NaY(MoO4)2:Eu3+
Authors: Zhang You-jin , Zhu Wei , He Hong-mei , Zheng Ao
Published: September 2013

Flower-like NaY(MoO4)2 particles were synthesized through a microwave-assisted hydrothermal process followed by a subsequent calcination process. The products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy. The possible formation mechanism of the flower-like NaY(MoO4)2 precursor was proposed. The NaY(MoO4)2:Eu3+ phosphors were also prepared and their luminescence properties showed the NaY(MoO4)2:Eu3+ materials with the emission peak at 612 nm had potential application as a red phosphor for white light-emitting diodes. Furthermore, the microwave-assisted hydrothermal process followed by a subsequent calcination process could be extended to prepare the other lanthanide molybdates with the flower-like morphology.
Photo-oxidation of Isoprene with Organic Seed: Estimates of Aerosol Size Distributions Evolution and Formation Rates
Authors: Cheng Yue , Hu Chang-jin , Gai Yan-bo , Gu Xue-jun , Zhao Wei-xiong , Huang Wei , Zhang Wei-jun
Published: September 2013

Indoor smog chamber experiments have been conducted to investigate the dynamics of secondary organic aerosol (SOA) formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investigated. It was shown that in the presence of high-level seed aerosol and low-level isoprene (typical urban atmospheric conditions), particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene (typical atmospheric conditions in rural region), bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles in different conditions were also estimated.
Leaf-galling phylloxera on grapes reprograms host metabolism and morphology
Authors: Nabity Paul D. , Haus Miranda J. , Berenbaum May R. , DeLucia Evan H.
Published: September 2013

Significance

Some herbivorous insects induce galls, abnormal structures, in their host plants, benefiting the gall-forming parasite by providing nutritive tissue. The gall-forming insect phylloxera induces stomata, openings through which plants regulate water and CO2, on the upper surface of grape leaves where they typically do not occur. Carbon uptake and transpiration by induced stomata facilitate nutrient acquisition by gall tissue and phylloxera. Moreover, gall formation reprograms the host-leaf transcriptome to increase transcripts associated with sucrose mobilization and glycolysis and decrease defense-related transcripts. Thus, stomata induction by phylloxera reconfigures leaves to increase carbon gain, to partially offset negative impacts of gall formation.
Reversible DNA methylation regulates seasonal photoperiodic time measurement
Authors: Stevenson Tyler J. , Prendergast Brian J.
Published: September 2013

Significance

This work examined whether epigenetic mechanisms participate in the regulation of seasonal reproduction. In long-day (summer) breeding hamsters, exposure to inhibitory winter photoperiods, or winter-like patterns of melatonin, altered DNA methyltransferase expression; decreased DNA methylation in the proximal promoter region of deiodinase type III (
dio3
) in the hypothalamus; and, in turn, increased hypothalamic
dio3
expression. Pharmacological blockade of photoperiod-driven demethylation attenuated reproductive responses to winter photoperiods. Winter demethylation was reversed in anticipation of spring: spontaneous reproductive development was accompanied by remethylation of the
dio3
promoter and decreases in
dio3
mRNA. Methylation dynamics in the adult brain are reversible and may constitute an important component of the mechanism by which seasonal time is represented in the nervous system.
Photoreceptor cells are major contributors to diabetes-induced oxidative stress and local inflammation in the retina
Authors: Du Yunpeng , Veenstra Alexander , Palczewski Krzysztof , Kern Timothy S.
Published: September 2013

Significance

Studies of diabetic retinopathy have focused especially on the retinal vasculature, but recent studies suggest that the neural retina also is involved. Oxidative stress and local inflammatory changes have been shown to play important roles in the pathogenesis of this retinopathy, but the source of reactive oxygen species has been less clear. We now show that most of the oxidative stress in retinas of diabetic mice emanates from neural photoreceptor cells, and elimination of these cells in diabetes inhibits both the oxidative stress and inflammatory changes shown to cause the vascular lesions of diabetic retinopathy. These studies suggest a mechanism by which neural cells can initiate the vascular injury characteristic of diabetic retinopathy.
Lexical Information of Persian Transitive Verbs during Sentence Comprehension
Authors: Mehrabi Masoumeh , Zaker Arman
Published: September 2013

This article investigates the nature of lexical information in the lexical entries of Persian transitive verbs. In the first experiment transitive verbs were categorized into five groups. What differentiates them is the number of argumental structural and subcategorization frame options of each verb. The question is: which one is more fundamental in sentence processing? In the second test the question is whether the number of argument(s) and complement(s) in each option determines processing time. Twenty normal native speakers of Farsi participated in these tests, divided into two groups. Cross-modal lexical decision method was used here. Using the DMDX software program the tests were performed and usingt-tests the data were analyzed. The results of the first test show that both the argumental structure and subcategorization frame possibilities of the verb can affect sentence processing time. Also the important role of the number of the complement(s) needed for a specific verb has been indicated by the second test results. Overall results show that the verb type of a sentence and sentence syntactic complexity determine the processing time. This has some implications for teaching Farsi to foreign language learners for whom knowing more verbs leads to making more grammatical sentences.
An initial study of transgender people's experiences of seeking and receiving counselling or psychotherapy in the UK
Authors: Hunt Jane
Published: September 2013

Background: There are no published empirical research studies exploring transgender people's experiences of seeking and receiving counselling or psychotherapy outside of gender identity clinics within the UK. As a result, counsellors know little about why transgender people seek counselling, who they seek counselling from, and what their experiences are of receiving counselling. Aim: To address this gap in the literature, this study investigated transgender people's experiences of seeking and receiving counselling or psychotherapy outside of gender identity clinics within the UK. Funding for this study was provided by a BACP Seedcorn grant. Method: A mixed method small‐scale qualitative research design was employed, comprising an online survey and five semi‐structured interviews. Findings: Participants tended to seek counselling on two or more occasions and received between 2 and 12 sessions. Participants sought counselling for common psychological concerns as well as gender identity and coming out issues. A fear of being discriminated against and exploring gender for the first time were significant barriers in seeking help. Participants reported mixed experiences of counselling but valued a therapeutic relationship in which they felt affirmed, listened to and understood. Discussion: The findings from this study mirror aspects of previous research conducted in the USA concerning transgender clients' experiences of counselling. However, these findings point to the importance of recognising the potential vulnerability transgender clients experience when seeking counselling and the need for therapists to develop greater awareness, knowledge and competence regarding working with transgender clients.
Distinct amino acid–sensing mTOR pathways regulate skeletal myogenesis
Authors: Yoon Mee-Sup , Chen Jie
Published: September 2013

Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinase–independent manner. Our results uncover amino acid–sensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling.
FPSAC: fast phylogenetic scaffolding of ancient contigs
Authors: Rajaraman Ashok , Tannier Eric , Chauve Cedric
Published: September 2013

Motivations: Recent progress in ancient DNA sequencing technologies and protocols has lead to the sequencing of whole ancient bacterial genomes, as illustrated by the recent sequence of the Yersinia pestis strain that caused the Black Death pandemic. However, sequencing ancient genomes raises specific problems, because of the decay and fragmentation of ancient DNA among others, making the scaffolding of ancient contigs challenging.

Results: We show that computational paleogenomics methods aimed at reconstructing the organization of ancestral genomes from the comparison of extant genomes can be adapted to correct, order and orient ancient bacterial contigs. We describe the method FPSAC (fast phylogenetic scaffolding of ancient contigs) and apply it on a set of 2134 ancient contigs assembled from the recently sequenced Black Death agent genome. We obtain a unique scaffold for the whole chromosome of this ancient genome that allows to gain precise insights into the structural evolution of the Yersinia clade.

Availability and Implementation: Code, data and results are available at http://paleogenomics.irmacs.sfu.ca/FPSAC.

Contact:  cedric.chauve@sfu.ca

Supplementary information:  Supplementary data are available at Bioinformatics online.
On the progenitor of the Type Ic SN 2013dk in the Antennae galaxies
Authors: Elias-Rosa N. , Pastorello A. , Maund J. R. , Takáts K. , Fraser M. , Smartt S. J. , Benetti S. , Pignata G. , Sand D. , Valenti S.
Published: September 2013

We report the results of our search for the progenitor candidate of SN 2013dk, a Type Ic supernova (SN) that exploded in the Antennae galaxy system. We compare pre-explosion Hubble Space Telescope (HST) archival images with SN images obtained using adaptive optics at the ESO Very Large Telescope. We isolate the SN position to within 3σ uncertainty radius of 0.02 arcsec and show that there is no detectable point source in any of the HST filter images within the error circle. We set an upper limit to the absolute magnitude of the progenitor to be MF555W ≳ −5.7, which does not allow Wolf–Rayet (WR) star progenitors to be ruled out. A bright source appears 0.17 arcsec away, which is either a single bright supergiant or compact cluster, given its absolute magnitude of MF555W = −9.02 ± 0.28 extended wings and complex environment. However, even if this is a cluster, the spatial displacement of SN 2013dk means that its membership is not assured. The strongest statement that we can make is that in the immediate environment of SN 2013dk (within 10 pc or so), we find no clear evidence of either a point source coincident with the SN or a young stellar cluster that could host a massive WR progenitor.
Analyzing the Robustness of Semi-Parametric Duration Models for the Study of Repeated Events
Authors: Box-Steffensmeier Janet M. , Linn Suzanna , Smidt Corwin D.
Published: September 2013

Estimators within the Cox family are often used to estimate models for repeated events. Yet, there is much we still do not know about the performance of these estimators. In particular, we do not know how they perform given time dependence, different censoring rates, and a varying number of events and sample sizes. We use Monte Carlo simulations to demonstrate the performance of a variety of popular semi-parametric estimators as these data aspects change and under conditions of event dependence and heterogeneity, both, or neither. We conclude that the conditional frailty model outperforms other standard estimators under a wide array of data-generating processes, and data limitations rarely alter its performance.
Take-off aided by magnetic levitation technology
Authors: Robert Majka Andrzej
Published: September 2013

Purpose

– The purpose of the paper is to analyze changes in the selected characteristics of an aircraft aided by a ground-based system using magnetic levitation (MAGLEV) to support safe take-off.

Design/methodology/approach

– The analysis of the mass characteristics of the main aircraft units with conventional constructing solutions was carried out in this paper. It allowed determining the mass of these units and verifying the obtained results on the basis of the known examples. Thanks to such an approach it was possible to determine the mass of the aircraft modified for the requirements of the ground and on-board system for support of the aircraft safe take-off and landing (GABRIEL) system taking into account the change in the weights of the modified units (fuselage, wings, power unit, landing gear, etc.). The weight of the aircraft in its basic version was determined on the basis of the common knowledge and methods described in the scientific literature which are based on the statistical analysis. The weight of the modified units for the needs of the GABRIEL system was determined on the basis of similar formulas taking into account the constructional changes in the airframe. The thrust required of the power unit was determined on the basis of the analysis of the steady state of the horizontal flight for the calculating aerodynamic characteristics determined by conventional methods. The characteristics in the take-off phase were determined solving the equation of motion of the aircraft influenced by the aerodynamic, electrodynamic forces and the forces that come from the power unit.

Findings

– The preliminary analysis shows that the take-off aid system that uses the phenomenon of MAGLEV is possible to be created using the present-day technology. However, the costs of its realization would make it economically unproved. But it could increase safety and reduce harmful influence on the environment caused by taking-off and landing aircrafts.

Research limitations/implications

– The analysis was carried out only for one chosen version of the solution which according to the author has the greatest chance to succeed. At the present-day state of the art, it seems problematic to use the proposed system to aid landing.

Practical implications

– The work shows a practical possibility to implement the proposed solution. The results of the analyses are a separate point for further research of similar systems.

Originality/value

– The work presents one of the aspects of the potential application of the innovatory conception of take-off and landing aid of transport aircrafts by the ground-based system using the MAGLEV technology.
Defining influence of load conditions on distribution and value of stresses in dual-power-path gear wheels applying FEM
Authors: Budzik Grzegorz , Kozik Bogdan , Pacana Jacek
Published: September 2013

Purpose

– The analysis, carried out for this publication, concerned checking the nature of mating of gear wheels with different load conditions. The computation was made applying FEM in Abaqus 6.10-1 program and concerned spur gears in dual-power-path gears made of ABS. The same geometrical models, material parameters and boundary conditions were assumed for all the analysed stages of the computation. However, the values of torque transmitted from active wheels to passive wheel of the gearing were changed. The paper aims to discuss these issues.

Design/methodology/approach

– Observing changes of stress levels for toothed wheel and pinions allows to state that for relatively low load values, bending stresses at tooth root change proportionally to the change of the applied load.

Findings

– Values of contact stresses on mating teeth flanks were also defined for the most loaded part of the dual-power-path gearing, namely for a pinion. In case of contact stresses, it was observed that together with constant increase of torque value, the values of stresses change but the nature of these changes is not proportional to the applied load. Out of all the analysed variants, the most favourable, from the point of view of durability, was the situation in initial (theoretical) model with regular power division on all mating wheels.

Originality/value

– Conclusions drawn as a result of numerical computation are helpful in defining the nature of work of dual-power-path gearing in different load conditions and will be compared to results of stand tests of the analysed gearing.
Engine and multitask airplane integration: criteria of engine parameters selection
Authors: Wygonik Piotr
Published: September 2013

Purpose

– The paper aims to present a way of engine model integration, an aircraft (multitask) and the mission into the single model that allows to study, from the level of selection of the engine cycle parameters, the feasibility of a specific mission with the assumed aerodynamic characteristics exemplified by a multitask airplane.

Design/methodology/approach

– There were introduced dimensionless geometric and energetic criteria, binding parameters of the engine and the airplane. The following models were built: of the turbofan engine and the aircraft movements with the application of these criteria, creating a dimensionless model allowing for measuring the impact of engine design parameters on the efficiency of the mission undertaken.

Findings

– The results were limited to the presentation of the impact of circuit parameters, such as engine TIT, OPR, BR on the defined criteria. The application of dimensionless criteria reduced the dimension of the task.

Practical implications

– The presented method can be useful for engineers involved in the task of engine integration and the airplane at the preliminary design stage.

Originality/value

– The originality of the presented solutions is reduced to provide a different, unconventional approach to the design process and not (so far) the engine itself but the entire aviation system.
Lessons learned from a part-time worker typology applied to full-timers
Authors: Lynn-Senter Wittmer Jenell , E. Martin James
Published: September 2013

Purpose

– Research on work status differences has yielded inconsistent results and is not relevant for today's workforce, economic circumstances, or the changing nature of work. Inconsistencies may be due to substantial heterogeneity, rather than homogeneity, within each group (part-time (PT) and full-time (FT)). Thus, researchers created a PT worker typology based on demographics and personal life roles. Systematic differences in attitudes and behaviors across derived groups of PT workers were found. The purpose of the current study is to test the applicability of this PT worker typology on FT workers and to extend the typology's foundational theory, partial inclusion theory (PIT).

Design/methodology/approach

– The current study employs cluster analysis on three diverse samples (n=3,747) to establish a basis for the generalizability of the FT typology.

Findings

– Strong support was found for a similar, but distinct, FT employee typology. Attitudinal and behavioral differences were also found among the various FT groups which were similar to the differences found among the PT groups.

Research limitations/implications

– The current study has implications both for the application of PIT as well management and human resources. Targeted wellness and retention programs can be designed for various groups of FT employees, including scheduling flexibility and benefit plans.

Originality/value

– This is one of the first studies to examine the heterogeneity of the FT workforce, understanding that FT workers also have substantial life roles outside of work that likely affect their involvement and attitudes at work.
Corporate financial policies in emerging markets: the role of financial market development
Authors: Amo-Yartey Charles , Abor Joshua
Published: September 2013

Purpose

– The paper aims to study the importance of financial market development and financial structure in explaining the financial policies of firms in emerging market countries.

Design/methodology/approach

– The paper uses a panel data of 32 countries and the system generalized method of moments approach.

Findings

– The analysis shows that stock market development is associated with higher use of external finance relative to internal finance, while bond market development is associated with lower use of external finance relative to internal finance. The findings of this study also indicate that stock market development tends to shift the policies of firms towards less debt and more equity, and bond market development is associated with higher debt and less equity in emerging economies.

Originality/value

– The value of this study is in respect of its contribution to the extant literature on corporate financial policies in emerging market economies.
How do managers make sense of strategy?
Authors: Grazzini Frédérique
Published: September 2013

Purpose

– As a result of the global financial crisis, the meaning of action has reemerged as a central focus of the current debates. This paper seeks to analyze the meaning given by managers to their contribution to the strategy development process.

Design/methodology/approach

– The core underlying assumptions in this research are that social phenomena such as strategy are determined by representations shaped by discourse and that education is a major vector for promoting strategic discourses. Through the concepts of social representation and strategy lens, the paper examines the beliefs and paradigms underlying the strategy development process. Based on a sample of 1,033 managers, this research constructs a holistic typology of the social representations of strategy among managers.

Findings

– Four different groups of social representations of strategy are identified and characterized. Links are established between these groups and a range of socio-demographic, social, occupational and structural variables.

Practical implications

– By clarifying various paradigms and providing reference points, this research encourages increased awareness of these paradigms among managers in order to promote emancipation from them.

Originality/value

– The study is primarily synthesis-based at a theoretical level, but also in the analysis and interpretation of the role of strategists. It also helps to close the gap between research, teaching and practice.
Contractors perspective toward factors affecting labor productivity in building construction
Authors: Mahamid Ibrahim
Published: September 2013

Purpose

– The study aims at identifying the factors affecting labor productivity in building construction projects in the West Bank in Palestine from contractors’ viewpoint.

Design/methodology/approach

– To do so, 59 contractors working in building construction completed a structured questionnaire survey and the factors were ranked according to their levels of influence. In all, 31 factors were identified through literature review. These factors were grouped into five groups: labor, managerial, materials and equipments, environmental, and financial.

Findings

– The analysis of the identified 31 factors indicates that the top-five factors negatively affecting labor productivity in building construction are: rework, lack of cooperation and communication between construction parties, financial status of the owner, lack of labor experience, and lack in materials.

Originality/value

– This study is original and has not been published before. The findings and recommendations of this study are very useful and helpful for the local firms and the international firms who are planning to do works in the West Bank
Exploring the link between organisational justice and job satisfaction and performance in Ghanaian hospitals
Authors: Abekah-Nkrumah Gordon , Ayimbillah Atinga Roger
Published: September 2013

Purpose

– The purpose of this paper is to examine whether organisational justice (distributive justice, procedural justice and interactional justice) predicts job satisfaction and performance of health professionals and whether the demographic characteristics of hospital employees mediate the relationship between workplace justice and job satisfaction and performance.

Design/methodology/approach

– Questionnaires were administered to a sample of 300 respondents in seven hospitals using convenient sampling. Hypotheses were tested using multiple and hierarchical regression models.

Findings

– The paper established that distributive justice, procedural justice and interactional justice predict job satisfaction and performance of health professionals. However, their demographic characteristics are shown to partially mediate the relationship between organisational justice and job satisfaction but not performance.

Originality/value

– Granted that other studies exist, this is one of the few that focuses on hospitals and probably the first of its kind in Ghanaian hospitals. Thus the findings could be essential for policy and practice and also generate further discourse that may improve the extant literature and our understanding of the subject.