bluuebunny/crossref_metadata_2025 huggingface dataset:
QSAR studies on Withanolide analogs for anticancer activity
Authors: Yadav Dharmendra Kumar , Khan Feroz , Sangwan Rajender S.
Published: November 2011

Withanolides are a group of pharmacologically active compounds present in most prodigal amounts in roots and leaves of Withania somnifera (Indian ginseng), one of the most important medicinal plants of Indian systems of medicine. Withanolides are basically steroidal lactones (highly oxygenated C-28 phytochemicals) and similar to ginsenosides activity. Some of the withanolides that have been reported possess immunomodulatory, and anticancer activities. In the present investigation, a quantitative structure activity relationship (QSAR) model based on forward stepwise multiple linear regression (MLR) has been developed against the MCF7, MCF7/BUS, and SK-Br-3 human solid tumor breast cancer cell lines. Relationship correlation coefficient (r2) and cross validation correlation coefficient (r2CV) of QSAR model were 0.77 and 0.73 for MCF7, 0.91 and 0.85 for MCF7/BUS, 0.93 and 0.90 for SK-Br-3 respectively. Developed QSAR model was also evaluated for prediction accuracy through internal, external and randomization validation methods. The QSAR study indicates that chemical descriptors viz., atom count (all atoms), connectivity index (order 2, standard), for MCF7, Connectivity Index (order 0, standard), Dipole Vector X (debye), Molar Refractivity, Shape Index (basic kappa, order 2) for SK-Br-3 and Atom Count (all atoms), Dielectric Energy (kcal/mole), Total Energy (Hartree), Heat of Formation (kcal/mole) for MCF7/BUS are correlate well with the breast cancer activity, Moreover, on the basis of screening for oral bioavailability, in silico ADME and toxicity risk assessment, we concluded that compounds W3, W4, W8 have markedly higher anticancer activity compared to control. These results can offer useful references for directing the molecular design of lead compound(s) based on withanolide or analogous template with improved activity.
Identification of Unique proteins of Candida albicans as Antifungal Drug Targets
Authors: Tripathi Himanshu , Meena Abha , Khan Feroz , Luqman Suaib
Published: November 2011

There are growing examples of drug resistance in the fungal pathogens to evade antifungal drugs by developing mutation in the key targeted enzymes and high expression of drug transporter genes including ABC transporters and MFS transporters. This led to the urgent need to identify novel (unique or essential to fungus) targets that can be used in development of potential antifungal drugs. We have used a comparative genomics approach to find out novel targets in opportunistic fungus, Candida albicans responsible for severe infection in immunocompromised humans. To identify novel targets we have analyzed available total 14,633 protein sequences (proteome) of C. albicans [SC5314] retrieved through RefSeq, an experimentally curated reference sequence database at NCBI, USA. To explore the unique proteins, proteome of C. albicans was first compared against human proteome and then with Saccharomyces cerevisiae (Yeast) through BLAST program (NCBI). Results showed that out of the available 14,633 protein sequences of C. albicans, 4,568 were identified unique when compared against human, while 2,955 were identified unique when compared against S. cerevisiae. Further work is ongoing to explore functionally known and unknown, unique or essential proteins/genes of C. albicans. Predicted as well as experimental data has been compiled in the form of a database namely, ‘CaTargetDB’, available at local internet LAN network of CIMAP.
Productivity and forage quality of a phytodiverse semi-natural grassland *under various management regimes
Authors: From Tatiana , Petersen Ute , Isselstein Johannes
Published: November 2011

Grassland management experiment (GrassMan) was set up in 2008 on a permanent semi-natural grassland in the Solling uplands, Germany. The main research focus is on the ecosystem functioning of the phytodiverse grassland (e.g. productivity and forage quality, water and nutrient fluxes). The aim of our study was to analyse the effects of vegetation composition and functional diversity on productivity and forage quality of the semi-natural permanent grassland. Variation in sward composition was achieved by herbicide application and resulted in three sward types: control sward type (without herbicide application), monocot-reduced and dicot-reduced. Further management factors included different nutrient input levels (without fertilizer and 180-30-100 kg/ha of N-P-K per year) and use intensity (cut once or three times a year). Functional diversity was determined by estimation of the yield shares for each species in the species composition and their specific functional characteristics. Forage quality was analysed by near infrared spectroscopy (NIRS). While sward type influenced the forage quality, yield variation was explained mainly by the management regime.
SDCCAG8 Obesity Alleles and Reduced Weight Loss After a Lifestyle Intervention in Overweight Children and Adolescents
Authors: Scherag André , Kleber Michaela , Boes Tanja , Kolbe Andreea‐Liliana , Ruth Anne , Grallert Harald , Illig Thomas , Heid Iris M. ,   The GIANT Consortium, Toschke André M. , Grau Katrine ,   The NUGENOB Consortium, Sørensen Thorkild I.A. , Hebebrand Johannes , Hinney Anke , Reinehr Thomas
Published: November 2011

Genome‐wide association analyses (GWAS) contributed to the detection of a number of single‐nucleotide polymorphisms (SNPs) associated with obesity. However, little is known about the impact of the obesity‐risk alleles on weight loss‐related phenotypes after lifestyle interventions. A recent meta‐analysis of GWAS reported five genomic loci near or in the genes FTO, MC4R, TMEM18, SDCCAG8, TNKS/MSRA that were associated with obesity in children and adolescents. Here, we analyzed the effect of the 10 SNPs representative of the five loci on measures of weight loss and cardiometabolic risk after a 1‐year lifestyle intervention in 401 children and adolescents (mean age 10.74 years; 55.4% female; mean BMI 27.42 kg/m2, mean BMI‐standard deviation score (SDS) 2.37). For confirmation of one locus genotyping of three intronic SNPs in SDCCAG8 was performed in 626 obese adults who completed the 10‐week hypoenergetic diet program. Intronic variants of SDCCAG8, which are associated with early onset obesity, are associated with reduced weight loss after a 1‐year lifestyle intervention in overweight children and adolescents even after adjusting for age, sex, baseline measurement, or multiple testing (all P < 10−6). However, our results could not be confirmed in 626 obese adults undertaking a hypoenergetic diet intervention.
Persistent oscillations of x-ray speckles: Pt (001) step flow
Authors: Pierce M. S. , Hennessy D. C. , Chang K. C. , Komanicky V. , Strzalka J. , Sandy A. , Barbour A. , You H.
Published: November 2011

We observed well-defined oscillations of speckle intensities from Pt (001) surfaces at high temperatures, persisting for tens of minutes. We used a model of hex-reconstructed terraces to show that the coherent x-rays reflected from the terraces retain their phases relative to the illumination boundary and the observed oscillations come from surface dynamics due to “step-flow” motion. Our results demonstrate a possibility that x-ray speckles can be applied to monitor the real-time evolution of surfaces.
Giant in-plane anisotropy in manganite thin films driven by strain-engineered double exchange interaction and electronic phase separation
Authors: Lu C. L. , Wu Y. Y. , Xia Z. C. , Yuan S. L. , Chen L. , Tian Z. M. , Liu J.-M. , Wu T.
Published: November 2011

We investigate epitaxial Pr0.65(Ca0.7Sr0.3)0.35MnO3 thin film grown on orthorhombic (110) NdGaO3 substrate which breaks the lattice symmetry and affects the phase separated ground state. As a result of the anisotropic substrate strain, giant in-plane magnetic and magnetotransport anisotropy are observed, which is related to the anisotropic coupling and competition between the double-exchange interaction and the Jahn-Teller distortion. Furthermore, the in-plane anisotropy shows a distinct enhancement near the metal-insulator transition, implying a significant contribution from the phase separation to the anisotropic transport behaviors.
The theoretical search for half-metallic material: The non-stoichiometric peroskite oxide Sr2FeCoO6−δ
Authors: Wu Haiping , Qian Yan , Tan Weishi , Xiao Chuanyun , Deng Kaiming , Lu Ruifeng
Published: November 2011

The non-stoichiometric peroskite oxide Sr2FeCoO6−δ is investigated and predicted to be half-metallic material using density-functional calculations. The results reveal that Sr2FeCoO5 shows antiferromagnetic half-metallic behavior and exhibits magnetic moment ordering with the magnetic moments of 2.97 and 3.72 μB on Fe(1) and Fe(2) sites, 2.96 and 3.20 μB on Co(1) and Co(2) sites antiparallel to those of Fe, and about 0.05 μB on O sites parallel to those of Co, respectively. Moreover, Sr2FeCoO4 and Sr2FeCoO6 both have half-metallic character. This hints that Sr2FeCoO6−δ possesses half-metallic nature in a large range of δ.
Dynamic processes in a silicate liquid from above melting to below the glass transition
Authors: Nascimento Marcio Luis Ferreira , Fokin Vladimir Mihailovich , Zanotto Edgar Dutra , Abyzov Alexander S.
Published: November 2011

We collect and critically analyze extensive literature data, including our own, on three important kinetic processes—viscous flow, crystal nucleation, and growth—in lithium disilicate (Li2O·2SiO2) over a wide temperature range, from above Tm to 0.98Tg where Tg ≈ 727 K is the calorimetric glass transition temperature and Tm = 1307 K, which is the melting point. We found that crystal growth mediated by screw dislocations is the most likely growth mechanism in this system. We then calculated the diffusion coefficients controlling crystal growth, $D_{eff}^U$DeffU, and completed the analyses by looking at the ionic diffusion coefficients of Li+1, O2−, and Si4+ estimated from experiments and molecular dynamic simulations. These values were then employed to estimate the effective volume diffusion coefficients, $D_{eff}^V$DeffV, resulting from their combination within a hypothetical Li2Si2O5 “molecule”. The similarity of the temperature dependencies of 1/η, where η is shear viscosity, and $D_{eff}^V$DeffV corroborates the validity of the Stokes-Einstein/Eyring equation (SEE) at high temperatures around Tm. Using the equality of $D_{eff}^V$DeffV and $D_{eff}^\eta$Deffη, we estimated the jump distance λ ∼ 2.70 Å from the SEE equation and showed that the values of $D_{eff}^U$DeffU have the same temperature dependence but exceed $D_{eff}^\eta$Deffη by about eightfold. The difference between $D_{eff}^\eta$Deffη and $D_{eff}^U$DeffU indicates that the former determines the process of mass transport in the bulk whereas the latter relates to the mobility of the structural units on the crystal/liquid interface. We then employed the values of η(T) reduced by eightfold to calculate the growth rates U(T). The resultant U(T) curve is consistent with experimental data until the temperature decreases to a decoupling temperature $T_d^U \approx 1.1 - 1.2T_g$TdU≈1.1−1.2Tg, when $D_{eff}^\eta$Deffη begins decrease with decreasing temperature faster than $D_{eff}^U$DeffU. A similar decoupling occurs between $D_{eff}^\eta$Deffη and $D_{eff}^\tau$Deffτ (estimated from nucleation time-lags) but at a lower temperature$T_d^\tau \approx T_g$Tdτ≈Tg. For T > Tg the values of $D_{eff}^\tau$Deffτ exceed $D_{eff}^\eta$Deffη only by twofold. The different behaviors of $D_{eff}^\tau (T)$Deffτ(T) and $D_{eff}^U (T)$DeffU(T) are likely caused by differences in the mechanisms of critical nuclei formation. Therefore, we have shown that at low undercoolings, viscosity data can be employed for quantitative analyses of crystal growth rates, but in the deeply supercooled liquid state, mass transport for crystal nucleation and growth are not controlled by viscosity. The origin of decoupling is assigned to spatially dynamic heterogeneity in glass-forming melts.
Relating the sequential dynamics of excitatory neural networks to synaptic cellular automata
Authors: Nekorkin V. I. , Dmitrichev A. S. , Kasatkin D. V. , Afraimovich V. S.
Published: November 2011

We have developed a new approach for the description of sequential dynamics of excitatory neural networks. Our approach is based on the dynamics of synapses possessing the short-term plasticity property. We suggest a model of such synapses in the form of a second-order system of nonlinear ODEs. In the framework of the model two types of responses are realized—the fast and the slow ones. Under some relations between their timescales a cellular automaton (CA) on the graph of connections is constructed. Such a CA has only a finite number of attractors and all of them are periodic orbits. The attractors of the CA determine the regimes of sequential dynamics of the original neural network, i.e., itineraries along the network and the times of successive firing of neurons in the form of bunches of spikes. We illustrate our approach on the example of a Morris-Lecar neural network.
On the effective permittivity of arrays of ferromagnetic wires
Authors: Liberal I. , Nefedov I. S. , Ederra I. , Gonzalo R. , Tretyakov S. A.
Published: November 2011

Interesting electromagnetic properties of ferromagnetic micro- and nanowires suggest that, by using them as inclusions in composite materials, artificial materials with novel and controllable properties can be realized. In this paper, we present a homogenization procedure to estimate the effective permittivity of dense (with respect to the wavelength) arrays of ferromagnetic wires. This general model can be applied to the design of systems based on ferromagnetic micro- and nanowires in the microwave and millimeter wave frequency ranges. The derived effective permittivity shows a complex frequency dispersion originated from the interplay between the geometry effects and the magnetic response of the ferromagnetic wires. Distinct phenomenology is observed as a function of the wire radius, which is studied in detail. Theoretical results are validated with numerical simulations.
Asymptotic properties of wall-induced chaotic mixing in point vortex pairs
Authors: Angilella Jean-Régis
Published: November 2011

The purpose of this work is to analyze the flow due to a potential point vortex pair in the vicinity of a symmetry line (or “wall”), in order to understand why the presence of the wall, even far from the vortices, accelerates fluid mixing around the vortex pair. An asymptotic analysis, in the limit of large distances to the wall, allows to approximate the wall effect as a constant translation of the vortex pair parallel to the wall, plus a straining flow which induces a natural blinking vortex mechanism with period half the rotation period. A Melnikov analysis of lagrangian particles, in the frame translating and rotating with the vortices, shows that a homoclinic bifurcation indeed occurs, so that the various separatrices located near the vortex pair (and rotating with it) do not survive when a wall is present. The thickness of the resulting inner stochastic layer is estimated by using the separatrix map method and is shown to scale like the inverse of the squared distance to the wall. This estimation provides a lower-bound to the numerical thickness measured from either Poincaré sections or simulations of lagrangian particles transported by the exact potential velocity field in the laboratory frame. In addition, it is shown that the outer homoclinic cycle, separating the vortices from the external (open) flow, is also perturbed from inside by the rotation of the vortex pair. As a consequence, a stochastic layer is shown to exist also in the vicinity of this cycle, allowing fluid exchange between the vortices and the outer flow. However, the thickness of this outer stochastic zone is observed to be much smaller than the one of the inner stochastic zone near vortices, as soon as the distance to the wall is large enough.
Vibrational characterization of dinaphthylpolyynes: A model system for the study of end-capped sp carbon chains
Authors: Cinquanta Eugenio , Ravagnan Luca , Castelli Ivano Eligio , Cataldo Franco , Manini Nicola , Onida Giovanni , Milani Paolo
Published: November 2011

We perform a systematic investigation of the resonance and vibrational properties of naphthyl-terminated sp carbon chains (dinaphthylpolyynes) by combined multi-wavelength resonant Raman (MWRR) spectroscopy, ultraviolet-visible spectroscopy, and Fourier-transform infrared (FT-IR) spectroscopy, plus ab initio density functional theory (DFT) calculations. We show that the MWWR and FT-IR spectroscopies are particularly suited to identify chains of different lengths and different terminations, respectively. By DFT calculations, we further extend those findings to sp carbon chains end-capped by other organic structures. The present analysis shows that combined MWRR and FT-IR provide a powerful tool to draw a complete picture of chemically stabilized sp carbon chains.
Guided propagation of surface acoustic waves and piezoelectric field enhancement in ZnO/GaAs systems
Authors: Pedrós J. , García-Gancedo L. , Ford C. J. B. , Barnes C. H. W. , Griffiths J. P. , Jones G. A. C. , Flewitt A. J.
Published: November 2011

The characteristics and dispersion of the distinct surface acoustic waves (SAWs) propagating in ZnO/GaAs heterostructures have been studied experimentally and theoretically. Besides the Rayleigh mode, strong Sezawa modes, which propagate confined in the overlayer, arise due to the smaller sound velocity in ZnO than in the substrate. The design parameters of the structure providing the strongest piezoelectric field at a given depth within the layered system for the different modes have been determined. The piezoelectric field of the Rayleigh mode is shown to be more than 10 times stronger at the interface region of the tailored ZnO/GaAs structure than at the surface region of the bulk GaAs, whereas the same comparison for the first Sezawa mode yields a factor of 2. This enhancement, together with the capacity of selecting waves with different piezoelectric and strain field depth profiles, will facilitate the development of SAW-modulated optoelectronic applications in GaAs-based systems.
A fast multichannel Martin-Puplett interferometer for electron cyclotron emission measurements on JET
Authors: Simonetto A. , Sozzi C. , Garavaglia S. , Fessey J. A. , Nowak S. ,   JET-EFDA Contributors
Published: November 2011

A Martin Puplett interferometer for electron cyclotron emission (ECE) measurements from JET tokamak plasmas was extended to multichannel operation for simultaneous radial and oblique ECE measurements. This paper describes the new optics and the instrument's performance.
Photodissociation of N2O: Triplet states and triplet channel
Authors: Schinke R. , Schmidt J. A. , Johnson M. S.
Published: November 2011

The role of triplet states in the UV photodissociation of \documentclass[12pt]{minimal}\begin{document}$\rm N_2O$\end{document}N2O is investigated by means of quantum mechanical wave packet calculations. Global potential energy surfaces are calculated for the lowest two 3A′ and the lowest two 3A′′ states at the multi-reference configuration interaction level of electronic structure theory using the augmented valence quadruple zeta atomic basis set. Because of extremely small transition dipole moments with the ground electronic state, excitation of the triplet states has only a marginal effect on the far red tail of the absorption cross section. The calculations do not show any hint of an increased absorption around 280 nm as claimed by early experimental studies. The peak observed in several electron energy loss spectra at 5.4 eV is unambiguously attributed to the lowest triplet state 13A′. Excitation of the 21A′ state and subsequent transition to the repulsive branch of the 23A′′ state at intermediate NN–O separations, promoted by spin-orbit coupling, is identified as the main pathway to the \documentclass[12pt]{minimal}\begin{document}${\rm N_2}(^1\Sigma _g^+)+{\rm O}(^3\!P)$\end{document}N2(1Σg+)+O(3P) triplet channel. The yield, determined in two-state wave packet calculations employing calculated spin-orbit matrix elements, is 0.002 as compared to 0.005 ± 0.002 measured by Nishida et al. [J. Phys. Chem. A 108, 2451 (2004)]10.1021/jp037034o.
Gröbner bases for finite-temperature quantum computing and their complexity
Authors: Crompton P. R.
Published: November 2011

Following the recent approach of using order domains to construct Gröbner bases from general projective varieties, we examine the parity and time-reversal arguments relating to the Wightman axioms of quantum field theory and propose that the definition of associativity in these axioms should be introduced a posteriori to the cluster property in order to generalize the anyon conjecture for quantum computing to indefinite metrics. We then show that this modification, which we define via ideal quotients, does not admit a faithful representation of the Braid group, because the generalized twisted inner automorphisms that we use to reintroduce associativity are only parity invariant for the prime spectra of the exterior algebra. We then use a coordinate prescription for the quantum deformations of toric varieties to show how a faithful representation of the Braid group can be reconstructed and argue that for a degree reverse lexicographic (monomial) ordered Gröbner basis, the complexity class of this problem is bounded quantum polynomial.
Thickness effect on nanoscale electromechanical activity in Pb(Mg1/3Nb2/3)O3-PbTiO3 thin films studied by piezoresponse force microscopy
Authors: Ferri A. , Detalle M. , Blach J.-F. , Warenghem M. , Rémiens D. , Desfeux R.
Published: November 2011

0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–PT) ferroelectric thin films with thickness ranging from 28 to 110 nm were sputter deposited onto LaNiO3/SiO2/Si substrates. Optical properties were determined by spectroscopic ellipsometry. We found B = 4.6 and λ0 = 209 nm, which is consistent for all PMN–PT samples with previous results shown in the literature. Nanoscale electromechanical activity was probed by using piezoresponse force microscopy in imaging and spectroscopic modes. Both piezoresponse images and local piezoloops recorded on each film highlighted an enhancement of piezoelectric vibration amplitude when the film thickness increased from 28 to 62 nm (∼1.06 to ∼1.34 mV), then saturation was observed for thicker films. This specific evolution was explained taking into account the low-permittivity interfacial Pb2Nb2O7 layer existing between bottom electrode and PMN-PT layer. Higher leakage current when thickness is decreasing was shown, which could also explain the particular behavior of the local electromechanical properties.
Sphere orderings representation of space-time
Authors: Vatandoost M. , Bahrampour Y.
Published: November 2011

A space-time may be regarded as a partially ordered set by causal relations. R. J. Low considered a continuous sphere order representation of a space-time and obtained some interesting results. However, some important questions about the conditions of continuity of this representation are still left unanswered. In this paper, we considered the problem of continuity and presented a partial solution for the set of all discontinuity points of a sphere order representation and constructed an example of a space-time which could not admit a sphere order representation with a special dimension. We also showed that, for a poset, the definition of the 2-sphere ordering dimension is equivalent to the definition of the 2-Euclidian dimension.
Spin-polarized transport in zigzag graphene nanoribbons with Rashba spin–orbit interaction
Authors: Kariminezhad M. , Namiranian A.
Published: November 2011

We have calculated spin-dependent conductance in zigzag graphene nanoribbons, attached to two leads, in the presence of Rashba spin−orbit interaction, based on the green function method. A tight binding model including Rashba spin-orbit interaction is used. It is shown that elements of conductance matrix crucially depend on the width and the length of the graphene nanoribbon for strong Rashba spin−orbit interaction.
Impact of carrier heating on backscattering in inversion layers
Authors: Clerc R. , Palestri P. , Selmi L. , Ghibaudo G.
Published: November 2011

In this work, Monte Carlo simulations and analytical modeling are used to investigate quasi-ballistic transport in nanometric metal oxide semiconductor field effect transistors (MOSFETs). In particular, we examine how the thermal nature of the distribution functions, which is implicitly assumed in the most common expression for the backscattering coefficient, leads to an underestimation of the backscattering coefficient in high field conditions and erroneous velocity distribution along the channel. An improved analytical model is proposed, which better captures the nonequilibrium nature of the distribution function and its impact on backscattering and by allowing velocity profiles to exceed the thermal limit. The improved model provides additional insights on the impact of several assumptions on backscattering and could serve as the basis for the development of physically based compact models of quasi-ballistic MOSFETs.
Microstructure, optical property, and electronic band structure of cuprous oxide thin films
Authors: Park Jun-Woo , Jang Hyungkeun , Kim Sung , Choi Suk-Ho , Lee Hosun , Kang Joongoo , Wei Su-Huai
Published: November 2011

Cuprous oxide (Cu2O) thin films were grown via radio frequency sputtering deposition at various temperatures. The dielectric functions and luminescence properties of the Cu2O thin films were measured using spectroscopic ellipsometry and photoluminescence, respectively. High-energy peaks were observed in the photoluminescence spectra. Several critical points (CPs) were found using second derivative spectra of the dielectric functions and the standard critical point model. The electronic band structure and the dielectric functions were calculated using density functional theory, and the CP energies were estimated to compare with the experimental data. We identified the high-energy photoluminescence peaks to quasi-direct transitions which arose from the granular structures of the Cu2O thin films.
Quantitative measurement of in-plane cantilever torsion for calibrating lateral piezoresponse force microscopy
Authors: Choi Hyunwoo , Hong Seungbum , No Kwangsoo
Published: November 2011

A simple quantitative measurement procedure of in-plane cantilever torsion for calibrating lateral piezoresponse force microscopy is presented. This technique enables one to determine the corresponding lateral inverse optical lever sensitivity (LIOLS) of the cantilever on the given sample. Piezoelectric coefficient, d31 of BaTiO3 single crystal (−81.62 ± 40.22 pm/V) which was calculated using the estimated LIOLS was in good agreement with the reported value in literature.
Soft x-ray array system with variable filters for the DIII-D tokamak
Authors: Hollmann E. M. , Chousal L. , Fisher R. K. , Hernandez R. , Jackson G. L. , Lanctot M. J. , Pidcoe S. V. , Shankara J. , Taussig D. A.
Published: November 2011

Recent upgrades to the soft x-ray (SXR) array system on the DIII-D tokamak are described. The system consists of two 32-channel arrays at one toroidal location and three toroidally distributed 12-channel arrays. The 32-channel arrays have been completely rebuilt to allow the switching of SXR filters without breaking vacuum. The 12-channel arrays have had upgrades performed to detectors, view slits, and data acquisition. Absolute extreme ultraviolet (AXUV) photodiodes are used as detectors in all arrays, allowing detection of photons ranging in energy from 2 eV to 10 keV. In the fixed-filter arrays, 127 μm Be filters are used. In the variable-filter arrays, filter wheels are used to switch between five different possible pinhole/filter combinations.
Note: Curve fit models for atomic force microscopy cantilever calibration in water
Authors: Kennedy Scott J. , Cole Daniel G. , Clark Robert L.
Published: November 2011

Atomic force microscopy stiffness calibrations performed on commercial instruments using the thermal noise method on the same cantilever in both air and water can vary by as much as 20% when a simple harmonic oscillator model and white noise are used in curve fitting. In this note, several fitting strategies are described that reduce this difference to about 11%.
Cu-doping of ZnO by nuclear transmutation
Authors: Selim F. A. , Tarun M. C. , Wall D. E. , Boatner L. A. , McCluskey M. D.
Published: November 2011

Zinc oxide single crystals were doped with copper acceptors by means of the nuclear transmutation doping method, which gives highly uniform dopant distributions and has a much higher probability of controlling the dopant locations in the lattice. The Cu doping was confirmed by the infrared absorption signature of Cu2+ at 5780 cm−1. Hall-effect measurements were performed to study the effect of CuZn on the electrical properties of ZnO. These measurements indicated that the Cu acceptor level lies 0.160 eV below the conduction-band minimum.
Strong modification of the reflection from birefringent layers of semiconductor nanowires by nanoshells
Authors: Diedenhofen S. L. , Algra R. E. , Bakkers E. P. A. M. , Gómez Rivas Jaime
Published: November 2011

The propagation of light in layers of vertically aligned nanowires is determined by their unique and extreme optical properties. Depending on the nanowire filling fraction and their diameter, layers of nanowires form strongly birefringent media. This large birefringence gives rise to sharp angle dependent peaks in polarized reflection. We demonstrate experimentally the tunability of the reflection by adding shells of SiO2 with thicknesses ranging from 10 nm to 30 nm around the nanowires. The strong modification of the reflection peaks renders nanowire layers as a promising candidate for sensing applications.
Enhanced piezoelectric response of BaTiO3–KNbO3 composites
Authors: Fujii Ichiro , Shimizu Shigehito , Yamashita Kenta , Nakashima Kouichi , Kumada Nobuhiro , Moriyoshi Chikako , Kuroiwa Yoshihiro , Fujikawa Yoshinori , Tanaka Daisuke , Furukawa Masahito , Wada Satoshi
Published: November 2011

The piezoelectric response of solvothermally synthesized BaTiO3 (BT)–KNbO3 (KN) composites (the nominal BT/KN ratio was 1) with distinct interfaces was investigated. The x-ray diffraction pattern showed two distinct peaks began to merge into a singular broad peak at a two-theta position between (200) and (002) tetragonal-related peaks of BT. The transmission electron microscopy observation showed a heteroepitaxial interface region between BT single-crystal particles and deposited KN crystals. The large-field piezoelectric constant was 136 pC/N, which was three times larger than that of a sintered 0.5BT–0.5KN composite. The enhanced piezoelectric response was attributed to the strained epitaxial interface region.
Photoinduced variable stiffness of spiropyran-based composites
Authors: Samoylova E. , Ceseracciu L. , Allione M. , Diaspro A. , Barone A. C. , Athanassiou A.
Published: November 2011

A quantitative demonstration of reversible stiffness upon appropriate light stimulus in a spiropyran-polymeric composite is presented. The polymeric films containing 3% wt. of the photochromic spiropyran were irradiated with alternating ultraviolet and visible light and the storage modulus was measured. A reversible change in modulus of about 7% was observed. The modulus change was attributed to an interaction of the polar merocyanine with the polymeric chains and/or to a variation of effective free volume induced by merocyanine aggregates formed in the polymer upon ultraviolet irradiation. The effect is fully reversed when the merocyanine isomers turn back to the spiropyran state after visible irradiation.
Strain control of orbital polarization and correlated metal-insulator transition in La2CoMnO6 from first principles
Authors: Lv Shuhui , Li Hongping , Wang Zhongchang , Han Lin , Liu Yao , Liu Xiaojuan , Meng Jian
Published: November 2011

Transition metal oxides show rich physical properties which are often influenced by external perturbation. Here, we report by first-principles calculations that strain enables switching of orbital occupancy of Co2+ in La2CoMnO6 and hence modifies electronic structure of La2CoMnO6. We find a metal-insulator transition in La2CoMnO6, which originates from the interplay between the strain induced lattice distortion and electron correlations. Such transition is understood upon the orbital polarization of Co2+, which takes on the dxz/yz character under compression, yet switches to the dx2-y2 character under tension. The orbital switching presented should hold promise for many technological applications.
High temperature oxygen near edge x-ray absorption fine structure valence band spectra and conductivity of LaFe3/4Ni1/4O3 from 300 to 773 K
Authors: Braun Artur , Erat Selma , Ariffin Ahmad K. , Manzke Recardo , Wadati Hiroki , Graule Thomas , Gauckler Ludwig J.
Published: November 2011

LaFe3/4Ni1/4O3 was subjected to oxygen near edge x-ray absorption fine structure spectroscopy for 300 K < T < 773 K. The spectra show in the pre-edge a small hole doped peak originating from Ni substitution. The relative spectral weight of this transition to the weight of the hybridized O(2p)-Fe(3d) transitions scales with T and has a maximum at around 600 K. The characteristic energies of the thermal activated spectral intensity and conductivity suggest that the concentration of charge transferred electrons from O(2p) to Ni(3d) increases and that the pre-edges account in part for the polaron activated transport.
Spin transfer torque switching assisted by thermally induced anisotropy reorientation in perpendicular magnetic tunnel junctions
Authors: Bandiera S. , Sousa R. C. , Marins de Castro M. , Ducruet C. , Portemont C. , Auffret S. , Vila L. , Prejbeanu I. L. , Rodmacq B. , Dieny B.
Published: November 2011

A method to switch the magnetization of the free layer in magnetic tunnel junctions with perpendicular anisotropy is demonstrated. It consists in assisting the spin transfer switching of the magnetization by a thermally induced reorientation of the free layer magnetic anisotropy from out-of-plane to in-plane. The junction temperature increase is due to the Joule dissipation around the tunnel barrier produced by the same pulse of current which generates the spin transfer torque. This magnetic reorientation allows the spin transfer torque efficiency to be maximal since the spin polarization of the current is perpendicular to the magnetization of the free layer. Such a thermally assisted switching allows designing highly down-size scalable magnetoresistive random access memory cells with improved write efficiency.
Distractor Filtering in Media Multitaskers
Authors: Cain Matthew S , Mitroff Stephen R
Published: November 2011

A growing amount of modern media is consumed simultaneously, a phenomenon known as ‘media multitasking’. Individuals who regularly engage in this activity, heavy media multitaskers (HMMs), are more affected by irrelevant information that can intrude into a primary task than are light media multitaskers (LMMs—Ophir et al, 2009 Proceedings of the National Academy of Sciences of the USA106 15583). However, the locus of this deficit is unknown, as previous research is consistent with both memory and attentional explanations. Here, we isolated attentional processes by employing a singleton distractor task with low working-memory demands. In this task, LMMs used top – down information to improve their performance, yet HMMs did not. This difference in performance in an established attentional capture task argues for the presence of attentional differences in HMMs and is consistent with the idea that HMMs maintain a wider attentional scope than LMMs, even when instructed otherwise.
Opposite changes in leaf dark respiration and soluble sugars with drought in two Mediterranean oaks
Authors: Rodríguez-Calcerrada Jesús , Shahin Oula , del Carmen del Rey María , Rambal Serge
Published: November 2011

The decline in net photosynthetic CO2 uptake (An) caused by drought could reduce the availability of soluble sugars and thus limit leaf dark respiration (Rd). We investigated the response of leaf gas exchange and nonstructural carbohydrates to drought by stopping watering to 2-year-old plants of Quercus ilex L. and Quercus pubescens Willd. grown in large pots. An declined with increasing water deficit more rapidly than Rd, and Rd declined slightly more steeply in Q. ilex than in Q. pubescens. Soluble sugars increased in drought-treated plants relative to control well watered plants, and the opposite pattern was found for starch. After rewatering, Rd returned to pre-drought rates within 2 days and An within 1 week. Soluble sugars tended to recover pre-drought values after rewatering but continued to be significantly higher in drought-treated than control plants of Q. pubescens, for which the increase in the concentration of soluble sugars had been higher. These results suggest that the relative production of soluble sugars is upregulated when An is limited, and that soluble sugars do not control respiratory rates in response to and recovery from water deficit. Rather, we suggest that the decline in Rd contributes to drought tolerance by reducing the consumption of soluble sugars, which play an important role as osmoprotectants during water deficit stress.
Phylogeny of the African ball-rolling dung beetle genus Epirinus Reiche (Coleoptera:Scarabaeidae:Scarabaeinae)
Authors: Mlambo S. , Sole C. L. , Scholtz C. H.
Published: November 2011

Recent phylogenetic analyses have pointed to the dung beetle genus Epirinus as the putative African ancestral roller group. Consequently, we tested the roller status of species in the genus with observational studies and constructed a molecular phylogeny based on partial sequences of two mitochondrial and two nuclear genes for 16 of 29 species. Tested species were confirmed to be dung rollers. Monophyly of the genus was confirmed, lending support to the synonymy of the wingless genus Endroedyantus with Epirinus. Moreover, the phylogenetic hypothesis was found to have a similar topology with a previously published one based on morphological data. A combined molecular and morphology analysis showed congruence between the molecular and morphological datasets. The loss of flight in some species and estimated divergence dates within Epirinus are discussed.
Climate variability of the Great Barrier Reef in relation to the tropical Pacific and El Niño-Southern Oscillation
Authors: Redondo-Rodriguez Ana , Weeks Scarla J. , Berkelmans Ray , Hoegh-Guldberg Ove , Lough Janice M.
Published: November 2011

Understanding the nature and causes of recent climate variability on the Great Barrier Reef (GBR), Australia, is fundamental to assessing the impacts of future climate change on this complex ecosystem. New analytical tools, improved data quality and resolution, longer time-series and new variables provide an opportunity to re-assess existing paradigms. Here, we examined sea surface temperature (SST), sea level pressure, surface winds, sea surface height and ocean currents for the period from 1948 to 2009. We focussed on the relationship between GBR surface climate and the wider tropical Pacific, and the influence of El Niño-Southern Oscillation (ENSO) events. Also, for the first time, we investigated the impact of the El Niño/La Niña Modoki phenomenon. Although neither type of ENSO event is a primary driver of inter-annual climate variability on the GBR, their influence is conspicuous. Classical ENSO events have a strong signature in the atmospheric circulation in the northern GBR but no significant relationship with SSTs and the opposite applies for the southern GBR. Conversely, El Niño/La Niña Modoki is significantly related to summer SSTs on the northern GBR, but not for the southern GBR. This study enhances our understanding of tropical Pacific and GBR climate drivers and will improve future predictions of change in climate variables that are likely to impact on the complex GBR ecosystem.
A biophysically-based neuromorphic model of spike rate- and timing-dependent plasticity
Authors: Rachmuth Guy , Shouval Harel Z. , Bear Mark F. , Poon Chi-Sang
Published: November 2011

Current advances in neuromorphic engineering have made it possible to emulate complex neuronal ion channel and intracellular ionic dynamics in real time using highly compact and power-efficient complementary metal-oxide-semiconductor (CMOS) analog very-large-scale-integrated circuit technology. Recently, there has been growing interest in the neuromorphic emulation of the spike-timing-dependent plasticity (STDP) Hebbian learning rule by phenomenological modeling using CMOS, memristor or other analog devices. Here, we propose a CMOS circuit implementation of a biophysically grounded neuromorphic (iono-neuromorphic) model of synaptic plasticity that is capable of capturing both the spike rate-dependent plasticity (SRDP, of the Bienenstock-Cooper-Munro or BCM type) and STDP rules. The iono-neuromorphic model reproduces bidirectional synaptic changes with NMDA receptor-dependent and intracellular calcium-mediated long-term potentiation or long-term depression assuming retrograde endocannabinoid signaling as a second coincidence detector. Changes in excitatory or inhibitory synaptic weights are registered and stored in a nonvolatile and compact digital format analogous to the discrete insertion and removal of AMPA or GABA receptor channels. The versatile Hebbian synapse device is applicable to a variety of neuroprosthesis, brain-machine interface, neurorobotics, neuromimetic computation, machine learning, and neural-inspired adaptive control problems.
Of veto players and entity-voting: institutional gridlock in the Bosnian reform process
Authors: Bahtić-Kunrath Birgit
Published: November 2011

Entity-voting in the Bosnian Parliamentary Assembly is a veto mechanism in Bosnia's consociational institutional setting and an important reason for the country's orientation towards the political status quo. An empirical analysis of the number and nature of adopted and rejected draft laws during the legislative period 2006–2010, embedded in George Tsebelis's veto player approach, leads to the conclusion that the veto players in the parliament – either delegates from Republika Srpska or delegates from the Federation of Bosnia and Herzegovina – have pushed the consociational system of checks and balances to its extremes. Entity-voting enables the veto players to “hijack” the parliament for their exclusionary ethnic interests and discourages cooperation and compromise between the veto players. Significant legislation, which in the present article is defined as legislation relevant for the European Partnership, faces severe obstacles to getting passed. In the light of these findings, the article discusses three policy implications: institutional redesign, a change of the actors, and an active role of the European Union for providing the actors with a realistically achievable goal which they equally share. This should reset the current calculus of self-interest and encourage cooperation between the veto players.
Politicization of identity in a European borderland: Istria, Croatia, and authenticity, 1990–2003
Authors: Ashbrook John
Published: November 2011

In most studies of the Balkans and Eastern Europe, identity politics focuses on nationalism. Unfortunately, very few examine regional identities and how they too are politicized in similar ways for similar reasons. Istria provides a good example of how identity is politicized and how and why individuals adapt it to both internal and external influences. While in the past local and regional identities were politicized in response to colonization, more recently national divisions became more prominent. However, in the very recent past, Istrian identity again became politicized as many natives drew lines between themselves and what they saw as an external national influence emanating from Zagreb. In the 1990s, a renewed Croatian national movement competed with an Istrian regional movement. Istrian regionalists, seeking to justify taking and maintaining regional power and hoping to more quickly bring Croatia into the European Union, used this new political tactic against the nationalizing Croatian government. While both the nationalists and the regionalists claimed the other side's ideology was foreign to Istria, in actuality both have historical roots in the region. Though the competition was not as virulent as in past episodes of nationalist tension between Italians and Croats, it does fit a pattern of continuity in the region.
From domestic to international: the politics of ethnic identity in Xinjiang and Inner Mongolia
Authors: Han Enze
Published: November 2011

This paper examines two contrasting cases of ethnic-group political activism in China – the Uighurs in Xinjiang and the Mongols in Inner Mongolia – to explain the former's political activism and the latter's lack thereof. Given similar challenges and pressures, how can we explain the divergent patterns in these two groups’ political behavior? This paper forwards the argument that domestic factors alone are not sufficient to account for differences in the groups’ political behavior. Instead, international factors have to be included to offer a fuller and satisfactory explanation. The paper illustrates how three types of international factors – big power support, external cultural ties, and Uighur diaspora community activism – have provided opportunities and resources to make the Uighur political activism sustainable. In Inner Mongolia, its quest for self-determination reached the highest fervor in the early half of the twentieth century, particularly with the support of imperial Japan. However, since the end of WWII, Inner Mongolia has not received any consistent international support and, as a result, has been more substantially incorporated into China's geopolitical body.
On socialization, patriotism and trust: the migration of homeward-bound Russian academics
Authors: Siegert Andreas
Published: November 2011

Because global labor markets affect the self-assignment of academics, they also affect structural changes in migration movements. To understand the migration patterns of highly qualified academic scholars, research has focused on their mobility, including their return migration. Thus far, studies have examined migrants from Latin America to the United States, but the impacts of cultural or societal contexts on migration have not been investigated.

Based on an empirical study of Russian academics who have migrated to Germany, we propose theory-based answers to the following questions: Is trust a relevant motivation for homeward-bound academic migrants to return to their native countries, and who or what is the object of this trust? Why do these migrants, in contrast to the vast majority of interviewees, self-identify with their society of origin? Does transaction cost theory explain these academics' motives for migration? Is their temporary stay beneficial to the host society?
Relevance of nationality in cross-border economic transactions
Authors: Bandelj Nina
Published: November 2011

How relevant is nationality in global economic behavior? The aim of this paper is to scrutinize the relevance of nationality affiliations and nationality conceptions in cross-border economic transactions, using the case of foreign investment exchanges. In particular, I examine how nationality affiliations may shape the types of commitments that actors will want to realize through foreign investment transactions, and how nationality categorizations influence the evaluation of potential partners in economic transactions. I also stipulate when nationality affiliations and categorizations play a more- or less-salient role. To develop these propositions I use illustrations from cases of foreign investment attempts in which investors from the West try to acquire firms in post-socialist Slovenia. The analysis is grounded in economic sociology and advances a relational understanding of nationality, seen as interpretive codes embedded in actors’ cultural repertoires, situationally invoked, and made relevant (or not) in interactions.