bluuebunny/crossref_metadata_2025 huggingface dataset:
Die computergestützte Aufmerksamkeitstestbatterie für Kinder (KITAP): Zusammenhänge mit dem Arbeitsgedächtnis und der Verarbeitungsgeschwindigkeit
Authors: Schöneck Nina , Schölmerich Axel
Published: June 2013

Die vorliegende Studie überprüft Zusammenhänge zwischen verschiedenen Aspekten der Aufmerksamkeit (Subtests der KITAP: Ablenkbarkeit, Alertness, Flexibilität, geteilte Aufmerksamkeit und Go/NoGo) mit kognitiven Leistungen (Subskalen im HAWIK-IV: Verarbeitungsgeschwindigkeit und Arbeitsgedächtnis). Dazu wurden N = 456 Kinder (52.2 % Jungen) im Alter von 7 bis 10 Jahren (M = 105 Monate, SD = 5.86) untersucht. Die Aspekte der Aufmerksamkeit ließen sich nicht überzeugend differenzieren, eine konfirmatorische Faktorenanalyse ergab zwei latente Variablen (Leistungsgeschwindigkeit und Leistungsgüte) mit gutem Modellfit. Die Leistungsgüte hängt signifikant mit dem Arbeitsgedächtnis und der Verarbeitungsgeschwindigkeit zusammen (r = -.31 bzw. r = -.24). Die Leistungsgeschwindigkeit zeigt bedeutsame, aber niedrigere Zusammenhänge mit den kognitiven Leistungen. Folgerungen für die differenzierte Interpretation der KITAP-Subtests werden diskutiert.
Validity of the Interest-and Deprivation-Type Epistemic Curiosity Model in Germany
Authors: Litman Jordan A. , Mussel Patrick
Published: June 2013

Three studies were conducted to evaluate the validity of the interest (I) and deprivation (D) type epistemic curiosity (EC) distinction in three German samples. In Study 1 (N = 395) and Study 2 (N = 191), responses to German translations of the Epistemic Curiosity Scale and the Curiosity as a Feeling-of-Deprivation Scale were submitted to confirmatory factor analysis. The previously found 10-item 2-factor model ( Litman, 2008 ; Litman, Crowson, & Kolinski, 2010 ) had the best fit compared to competing models. In Study 1, Study 2, and Study 3 (N = 249), the I- and D-type EC scales correlated positively with intellectual stimulation measures, providing evidence of convergent validity. I-type EC correlated with enjoying new discoveries and ideas, whereas D-type EC was associated with persistence and solving problems, providing evidence of discrimination.
Nitric oxide inhibits CXCL12 expression in neuroinflammation
Authors: Petković Filip , Blaževski Jana , Momčilović Miljana , Mostarica Stojkovic Marija , Miljković Djordje
Published: June 2013

Chemokine CXCL12 (C‐X‐C motif chemokine ligand 12) restricts immune cell invasion of the central nervous system (CNS) and limits neuroinflammation in experimental autoimmune encephalomyelitis (EAE), an animal model of inflammatory and demyelinating disease of the CNS, multiple sclerosis (MS). Nitric oxide (NO), by contrast, predominantly contributes to CNS tissue destruction in MS and EAE. Thus, the influence of NO on CXCL12 in the inflamed CNS was investigated. Excess expression of inducible NO synthase was inversely correlated to CXCL12 gene expression in spinal cord homogenates of rats immunized to develop EAE. NO inhibited gene expression of CXCL12 in astrocytes and endothelial cells in vitro. The inhibition was paralleled with reduction of p38 mitogen‐activated protein kinase (MAPK) phosphorylation and it was mimicked with inhibitors of p38 MAPK activation in astrocytes. In vivo suppression of nitric generation recovered CXCL12 expression in the CNS and attenuated EAE in Dark Agouti rats. On the contrary, in vivo NO donation decreased CXCL12 expression in the CNS of EAE‐resistant Albino Oxford (AO) rats. However, the effect was not paralleled with induction of EAE in AO rats. It is suggested that NO acting through suppression of p38 MAPK inhibits CXCL12 expression in neuroinflammation. These results imply that downregulation of NO release and protection of CXCL12 expression within the CNS might present the potential approaches in MS therapy.
Nanomolar cholera toxininhibitors based on symmetrical pentavalent ganglioside GM1os-sym-corannulenes
Authors: Mattarella Martin , Garcia-Hartjes Jaime , Wennekes Tom , Zuilhof Han , Siegel Jay S.
Published: June 2013

Corannulene derivatives, functionalized,viacopper-catalyzed alkyne-azide cycloaddition (CuAAC) reactions, with galactose and the ganglioside GM1-oligosaccharide (GM1os), were evaluated for their ability to inhibit the binding of cholera toxin to its natural ligand; in this assay, GM1os-sym-corannulenes proved to be nanomolar inhibitors.
Crystal structures of S6K1 provide insights into the regulation mechanism of S6K1 by the hydrophobic motif
Authors: Wang Jianchuan , Zhong Chen , Wang Fang , Qu Fangfang , Ding Jianping
Published: June 2013

The activity of S6K1 (p70 ribosomal protein subunit 6 kinase 1) is stimulated by phosphorylation of Thr389 in the hydrophobic motif by mTORC1 (mammalian target of rapamycin complex 1) and phosphorylation of Thr229 in the activation loop by PDK1 (phosphoinositide-dependent kinase 1); however, the order of the two events is still ambiguous. In the present paper we report six crystal structures of the S6K1 kinase domain alone or plus the hydrophobic motif in various forms, in complexes with a highly specific inhibitor. The structural data, together with the biochemical data, reveal in vivo phosphorylation of Thr389 in the absence of Thr229 phosphorylation and demonstrate the importance of two conserved residues, Gln140 and Arg121, in the establishment of a hydrogen-bonding network between the N-lobe (N-terminal lobe) and the hydrophobic motif. Phosphorylation of Thr389 or introduction of a corresponding negatively charged group leads to reinforcement of the network and stabilization of helix αC. Furthermore, comparisons of S6K1 with other AGC (protein kinase A/protein kinase G/protein kinase C) family kinases suggest that the structural and sequence differences in the hydrophobic motif and helix αC account for their divergence in PDK1 dependency. Taken together, the results of the present study indicate that phosphorylation of the hydrophobic motif in S6K1 is independent of, and probably precedes and promotes, phosphorylation of the activation loop.
Structural insights into the inhibition of type VI effector Tae3 by its immunity protein Tai3
Authors: Dong Cheng , Zhang Heng , Gao Zeng-Qiang , Wang Wen-Jia , She Zhun , Liu Guang-Feng , Shen Yue-Quan , Su Xiao-Dong , Dong Yu-Hui
Published: June 2013

The recently described T6SS (type VI secretion system) acts as a needle that punctures the membrane of the target cells to deliver effector proteins. Type VI amidase effectors can be classified into four divergent families (Tae1–Tae4). These effectors are secreted into the periplasmic space of neighbouring cells via the T6SS and subsequently rupture peptidoglycan. However, the donor cells are protected from damage because of the presence of their cognate immunity proteins [Tai1 (type VI amidase immunity 1)–Tai4]. In the present paper, we describe the structure of Tae3 in complex with Tai3. The Tae3–Tai3 complex exists as a stable heterohexamer, which is composed of two Tae3 molecules and two Tai3 homodimers (Tae3–Tai34–Tae3). Tae3 shares a common NlpC/P60 fold, which consists of N-terminal and C-terminal subdomains. Structural analysis indicates that two unique loops around the catalytic cleft adopt a closed conformation, resulting in a narrow and extended groove involved in the binding of the substrate. The inhibition of Tae3 is attributed to the insertion of the Ω-loop (loop of α3–α4) of Tai3 into the catalytic groove. Furthermore, a cell viability assay confirmed that a conserved motif (Gln-Asp-Xaa) in Tai3 members may play a key role in the inhibition process. Taken together, the present study has revealed a novel inhibition mechanism and provides insights into the role played by T6SS in interspecific competition.
Pharmacological characteristics of Kv1.1- and Kv1.2-containing channels are influenced by the stoichiometry and positioning of their α subunits
Authors: Al-Sabi Ahmed , Kaza Seshu Kumar , Dolly J. Oliver , Wang Jiafu
Published: June 2013

Voltage-sensitive neuronal Kv1 channels composed of four α subunits and four associated auxiliary β subunits control neuronal excitability and neurotransmission. Limited information exists on the combinations of α subunit isoforms (i.e. Kv1.1–1.6) or their positions in the oligomers, and how these affect sensitivity to blockers. It is known that TEA (tetraethylammonium) inhibits Kv1.1 channels largely due to binding a critical tyrosine (Tyr379) in the pore, whereas Val381 at the equivalent location in Kv1.2 makes it insensitive. With the eventual aim of developing blockers for therapeutic purposes, Kv1.1 and 1.2 α subunit genes were concatenated to form combinations representing those in central neurons, followed by surface expression in HEK (human embryonic kidney)-293 cells as single-chain functional proteins. Patch-clamp recordings demonstrated the influences of the ratios and positioning of these α subunits on the biophysical and pharmacological properties of oligomeric K+ channels. Raising the ratio of Kv1.1 to Kv1.2 in Kv1.2-1.2-1.1-1.2 led to the resultant channels being more sensitive to TEA and also affected their biophysical parameters. Moreover, mutagenesis of one or more residues in the first Kv1.2 to resemble those in Kv1.1 increased TEA sensitivity only when it is adjacent to a Kv1.1 subunit, whereas placing a non-interactive subunit between these two diminished susceptibility. The findings of the present study support the possibility of α subunits being precisely arranged in Kv1 channels, rather than being randomly assembled. This is important in designing drugs with abilities to inhibit particular oligomeric Kv1 subtypes, with the goal of elevating neuronal excitability and improving neurotransmission in certain diseases.
Nonvolatile memory device based on SiO2/GaN/AlGaN/GaN heterostructure
Authors: Lee J.‐G. , Choi S. , Park B.‐R. , Seo K.‐S. , Kim H. , Cha H.‐Y.
Published: June 2013

Demonstrated is a nonvolatile memory device based on a SiO2/GaN/AlGaN/GaN heterostructure in which the upper GaN layer acted as a storage node. Charges were stored in and released from the upper GaN layer by applying positive and negative gate biases, respectively. The top SiO2 layer acted as a blocking layer. The threshold voltage shift was ∼ 3 V between the program and erase modes and the retention characteristics were very stable over 10000 s.
Electrically small complementary split‐ring resonator antenna on eighth‐mode substrate integrated waveguide
Authors: Sam S. , Lim S.
Published: June 2013

An electrically small substrate integrated waveguide (SIW) antenna is proposed at 5.22 GHz. Its electrical size is reduced by a complementary split‐ring resonator which is loaded on the eighth‐mode SIW (EMSIW). The EMSIW occupies only 12.5% of the conventional SIW with the same dominant resonant frequency. The S‐parameters and radiation patterns are investigated by full‐wave simulation and measurements. Results show the omnidirectional radiation pattern with a 4 dBi peak gain.
Tipping bucket data processing for propagation application
Authors: D'Amico M. , Jong S.L. , Riva C.
Published: June 2013

Rain attenuation prediction models at millimetre wavelengths require rain rate averaged over one minute. Currently available tipping bucket rain gauges often only provide the number of tips per minute (or a directly related quantity). In this reported work, the performance of a new algorithm devised to estimate rain rate from data gathered with such rain gauges, when used for propagation application, is investigated. To this purpose, an extensive database collected over a period of ten years is exploited. It is concluded that, even though the proposed algorithm performs well, the number of tips per minute may not be the best parameter to derive rain rate for propagation applications.
Compact Wilkinson power divider using two‐section asymmetrical T‐structures
Authors: Chang C.‐L. , Tseng C.‐H.
Published: June 2013

A compact planar Wilkinson power divider is proposed using two‐section asymmetrical T‐structures to achieve a significant size reduction and retain a mimic return‐loss bandwidth as compared with the conventional one. The asymmetrical T‐structure is realised by two series high‐impedance lines with unequal electrical lengths and a shunt low‐impedance line. The two‐section configuration has the advantage of decreasing the shunt stub size, and then achieving an optimally miniaturised circuit layout. The developed power divider has a 66.5% 15 dB return loss bandwidth and only occupies a 12.7% circuit size of the conventional one. The measured results of the developed power divider are in a good agreement with simulated results.
Unsupervised posture detection by smartphone accelerometer
Authors: Yurur O. , Liu C.‐H. , Moreno W.
Published: June 2013

Proposed is a light‐weight unsupervised decision tree based classification method to detect the user's postural actions, such as sitting, standing, walking and running as user states by analysing the data from a smartphone accelerometer sensor. The proposed method differs from other approaches by applying a sufficient number of signal processing features to exploit the sensory data without knowing any a priori information. Experiments show that the proposed method still makes a solid differentiation in user states (e.g. an above 90% overall accuracy) even when the sensor is operated under slower sampling frequencies.
Rapid synthesis of gallium oxide resistive random access memory by atomic force microscopy local anodic oxidation
Authors: Tsai J.T.H. , Hsu Chia‐Hsiang , Hsu Chia‐Yun , Yang Chu‐Shou
Published: June 2013

The fabrication of gallium oxide nanodots for the application of resistive random access memory (RRAM) using a process of atomic force microscopy (AFM) local anodic oxidation on an indium tin oxide conductive glass substrate is reported. In the atmospheric environment, an AFM probe tip contacts the gallium film locally. This gallium oxide nanodot acts as the insulator layer in a single unit of the RRAM. The structure describes the insulator layer (GaOx) sandwiched by the top (AFM tip) and bottom (Ga film) electrodes. Using current and voltage biased methods, the device switches from a high‐resistance state (HRS) to a low‐resistance state (LRS) and reset from LRS to HRS. Low read‐voltage is used to distinguish the high/low resistance to present the digital data. Presented results show the ability of atomic force microscopy anodic oxidation to produce 300 nm diameter gallium oxide nanodots on glass substrates for potentially high density RRAMs.
Timing phase noise reduction of modelocked quantum‐dot lasers by time‐delayed optoelectronic feedback
Authors: Drzewietzki L. , Breuer S. , Elsäßer W.
Published: June 2013

A novel optoelectronic‐feedback stabilisation scheme for passively modelocked semiconductor lasers is demonstrated. By electrical modulation of the absorber section with a signal directly obtained from the time‐delayed optical laser output, a significant broadband reduction of timing phase noise (TPN) is achieved without the use of a reference oscillator. The similarity to TPN measurement results obtained by an all‐optical feedback configuration suggests that the presented optoelectronic and the all‐optical feedback configuration are based on a common underlying TPN reduction mechanism.
Global output feedback stabilisation for a class of uncertain non‐linear systems
Authors: Zhai Jun‐yong , Ai Wei‐qing , Fei Shu‐min
Published: June 2013

This study addresses the problem of global stabilisation by output feedback for a class of uncertain non‐linear systems whose output functions are not precisely known. To solve the problem, the authors first construct a new observer and then use the adding one power integrator technique to design a linear controller to globally stabilise the uncertain non‐linear system. It is shown that global exponential stability of the closed‐loop system is guaranteed by an appropriate choice of the design parameters.
Distributed output regulation of switching multi‐agent systems subject to input saturation
Authors: Wang Xiaoli , Ni Wei , Yang Jie
Published: June 2013

In this study, we consider the distributed output regulation (DOR) problem of linear multi‐agent systems subject to input saturation with switching topology. Owing to the input saturation elements, the considered systems is non‐linear. It is natural to take the semiglobal frame for it which allows one to use distributed linear feedback controller. The basic problem is to design distributed feedback controller for the considered multi‐agent systems in order to have all agents to track an active leader and/or distributed rejection with disturbance signals. Both the leader and the disturbance signal are modelled as the exogenous system with different dynamics and unmeasurable variables. A systematic distributed linear design approach based on the solvability condition is proposed for the considered DOR problem.
Design and implementation of decoupled compensation for a twin rotor multiple‐input and multiple‐output system
Authors: Pradhan Jatin Kumar , Ghosh Arun
Published: June 2013

This study achieves compensation of a physical twin rotor multiple‐input and multiple‐output system in two steps: (i) input–output decoupling its transfer function model, obtained by linearising its non‐linear model around an operating point, using an open‐loop, minimal precompensator and (ii) effecting 2‐degree of freedom single‐input and single‐output (SISO) compensations for the resulting SISO‐decoupled units. While step (i) ensures decoupling in the responses, the other performances (such as robustness, tracking, disturbance rejection, etc.) can be achieved using SISO compensations in step (ii) above. The performances of the compensated system in respect of decoupling, loop robustness and disturbance rejection are verified through simulations and experiments. The results are also compared with the existing ones.
General framework in designing Luenberger‐like non‐linear observer
Authors: Ekramian Mohsen , Hosseinnia Saeed , Sheikholeslam Farid
Published: June 2013

The problem of designing Luenberger‐like observer for non‐linear Lipschitz systems is addressed. Based on using the coordinate transformation, the author classify many practical approaches of observer synthesis into direct and indirect methods. A generalised Lipschitz condition and the related stability condition are then employed to establish a general framework in designing the Luenberger‐like observer dealing with both methods. Moreover, the proposed framework is interpreted in terms of some linear matrix inequalities (LMIs) which allows using numerical techniques to obtain a reduced order observer. Finally, some simulation examples are given to exhibit the effectiveness of the proposed observer synthesis approach.
Gradient‐based and least‐squares‐based iterative algorithms for Hammerstein systems using the hierarchical identification principle
Authors: Ding Feng , Liu Xinggao , Chu Jian
Published: June 2013

This study derives a least‐squares‐based iterative algorithm and a gradient‐based iterative algorithm for Hammerstein systems using the decomposition‐based hierarchical identification principle. The simulation results confirm that the proposed two algorithms can give satisfactory identification accuracies and the least‐squares‐based iterative algorithm has faster convergence rates than the gradient‐based iterative algorithm.
A class of adaptive robust state observers with simpler structure for uncertain non‐linear systems with time‐varying delays
Authors: Wu Hansheng
Published: June 2013

The problem of adaptive robust state observer design is considered for a class of uncertain non‐linear dynamical systems with multiple time‐varying delays. It is assumed that the upper bounds of the non‐linear delayed state perturbations are unknown and that the time‐varying delays are any non‐negative continuous and bounded functions, which do not require that their derivatives have to be less than one. In particular, it is only required that the non‐linear uncertainties, which can also include time‐varying delays, are bounded in any non‐negative non‐linear functions, which are not required to be known for the system designer. For such a class of uncertain non‐linear time‐delay systems, a new method is presented whereby a class of memoryless adaptive robust state observers with a rather simpler structure is proposed. It is also shown that by employing the proposed adaptive robust state observer, the observation error between the observer state estimate and the true state can be guaranteed to be uniformly exponentially convergent towards a ball, which can be as small as desired, in the presence of significant uncertainties and time delays. Finally, a numerical example is given to demonstrate the validity of the results.
Finite‐time stabilisation for Markov jump systems with Gaussian transition probabilities
Authors: Luan Xiaoli , Shi Peng , Liu Fei
Published: June 2013

The problems of finite‐time analysis and design for a class of Markov jump systems with Gaussian transition probabilities (TPs) are investigated in this study. Gaussian TP density function is introduced to quantise the stochastic uncertain information of TPs. Mode‐dependent and variation‐dependent controller is designed to make the resulting closed‐loop systems finite‐time bounded and finite‐time stabilisable for all admissible unknown external disturbances and random uncertain TPs. It is shown that the approach proposed in the paper dealing with TPs outperforms available ones in literature to date, which is also confirmed by a numerical example.
Consensus of fractional‐order heterogeneous multi‐agent systems
Authors: Yin Xiuxia , Yue Dong , Hu Songlin
Published: June 2013

This study is devoted to the consensus protocols design for a set of fractional‐order heterogeneous agents, which is composed of two kinds of agents differed by their dynamics and the fractional‐order α satisfies 0 < α < 2. Distributed state feedback consensus protocols are constructed for the two kinds of agents, respectively. Based on the Kronecker product technique and the fractional‐order stability theory, sufficient conditions are derived to ensure the consensus of heterogeneous multi‐agent systems in terms of linear matrix inequalities (LMIs). These can be solved numerically by LMI toolbox in Matlab. Finally, a simulation example is employed to validate the effectiveness of the theoretical results.
Adaptive fault‐tolerant robust control for a linear system with adaptive fault identification
Authors: Shen Yi , Liu Lijun , Dowell Earl H.
Published: June 2013

An integrated design of the adaptive robust control and the fault identification for a linear system with actuator faults is proposed. When actuators suffer from unpredicted faults, the proposed control strategy can track the actuator fault parameters adaptively without any prior fault information, and guarantee the robustness of the faulty system. An unknown input observer is designed to decouple the disturbance and the actuator faults. Then an adaptive control law with projection is presented to track the fault parameters. A new definition of robust H∞ ‐like performance is proposed to ensure that the system is robust for both exogenous disturbance and unpredicted faults. Then the adaptive robust control law is designed to guarantee the system satisfying the robust H∞ ‐like performance. Finally, the effectiveness of this control strategy is illustrated through the fault‐tolerant longitudinal control of the simplified F‐18 aircraft model.
Measurements and analysis of the radar signature of a new wind turbine design at X‐band
Authors: Balleri Alessio , Al‐Armaghany Allann , Griffiths Hugh , Tong Kinfai , Matsuura Takashi , Karasudani Takashi , Ohya Yuji
Published: June 2013

The authors study the radar signature of a new type of wind turbine, named the Wind Lens. This design includes a flanged shroud around the turbine which concentrates the wind flow past the turbine blades and hence improves the efficiency. The design also offers improved safety and reduces acoustic noise. Furthermore, it may offer a significantly lower radar signature, which may make the design much more attractive for use in situations where conventional wind turbine designs may disturb the operation of radars. The authors present the results of an experimental trial, carried out in the UK, to measure the radar cross section (RCS) of a 5 kW Wind Lens turbine prototype and provide a reference database that can be used for comparing the Wind Lens RCS with that of conventional turbines. The authors also investigate the methods to further reduce the Wind Lens RCS and present the results of a time‐varying Doppler analysis. The results show that the addition of a metallic mesh around the shroud obscures the rotating blades, and hence mitigates the RCS by 15 dB, at angles where the radar interference is highest.
Codeless processing of binary offset carrier modulated signals
Authors: Borio Daniele , Rao Marco , O'Driscoll Cillian
Published: June 2013

Advanced and unexpected applications are recently raising new interest in Global Navigation Satellite System (GNSS) codeless techniques that can be used, for example, for signal authentication and spoofing detection. Moreover, the presence of a subcarrier in modern GNSS signals introduces new challenges and opportunities. To take advantage of modern signal structures, codeless processing needs to be modified to recover the subcarrier which can subsequently be used for signal quality monitoring. In this study, codeless tracking is modified for processing binary offset carrier (BOC) modulated signals where a subcarrier lock loop is used to remove the subcarrier component. The performance of the suggested architecture is thoroughly analysed and theoretical results are supported by Monte Carlo simulations. An open‐loop, multi‐correlator codeless architecture is also proposed to monitor the BOC subcarrier correlation function. The effectiveness of the proposed codeless framework is demonstrated using real data collected from the Galileo in‐orbit validation satellites. The analysis supports the validity of the proposed architecture which enables quality monitoring of encrypted GNSS signals.
Energy‐efficient distributed approach for clustering‐based fault detection and diagnosis in image sensor networks
Authors: Mahapatro Arunanshu , Khilar Pabitra Mohan
Published: June 2013

This study proposes an algorithm for the design of a distributed protocol for detecting and diagnosing permanent faults in wireless image sensor networks (WISNs). This work explicitly takes into account the possibility of faults in different sections of the image sensor node and communication channel. The fault diagnosis is achieved by disseminating local decision made at each node. Theoretical analysis and simulation results show that high level (>0.95) of diagnosis accuracy can be achieved for a wide range of fault rates. Correctness and complexity proofs are provided, and they show that the proposed algorithm performs better than the existing protocols from both communication and energy complexity perspective. Analytical study shows that time complexity is O (nc) and message complexity O (n) for an n ‐node WISN where nc is the number of cluster heads.
Buckling-driven delamination of carbon nanotube forests
Authors: Pour Shahid Saeed Abadi Parisa , Hutchens Shelby B. , Greer Julia R. , Cola Baratunde A. , Graham Samuel
Published: June 2013

We report buckling-driven delamination of carbon nanotube (CNT) forests from their growth substrates when subjected to compression. Macroscale compression experiments reveal local delamination at the CNT forest-substrate interface. Results of microscale flat punch indentations indicate that enhanced CNT interlocking at the top surface of the forest accomplished by application of a metal coating causes delamination of the forest from the growth substrate, a phenomenon not observed in indentation of as-grown CNT forests. We postulate that the post-buckling tensile stresses that develop at the base of the CNT forests serve as the driving force for delamination.
Sensitive dependence on initial conditions in gene networks
Authors: Machina A. , Edwards R. , van den Driessche P.
Published: June 2013

Active regulation in gene networks poses mathematical challenges that have led to conflicting approaches to analysis. Competing regulation that keeps concentrations of some transcription factors at or near threshold values leads to so-called singular dynamics when steeply sigmoidal interactions are approximated by step functions. An extension, due to Artstein and coauthors, of the classical singular perturbation approach was suggested as an appropriate way to handle the complex situation where non-trivial dynamics, such as a limit cycle, of fast variables occur in switching domains. This non-trivial behaviour can occur when a gene regulates multiple other genes at the same threshold. Here, it is shown that it is possible for nonuniqueness to arise in such a system in the case of limiting step-function interactions. This nonuniqueness is reminiscent of but not identical to the nonuniqueness of Filippov solutions. More realistic gene network models have sigmoidal interactions, however, and in the example considered here, it is shown numerically that the corresponding phenomenon in smooth systems is a sensitivity to initial conditions that leads in the limit to densely interwoven basins of attraction of different fixed point attractors.
Cross sections for elastic scattering of electrons by CF3Cl, CF2Cl2, and CFCl3
Authors: Hoshino M. , Horie M. , Kato H. , Blanco F. , García G. , Limão-Vieira P. , Sullivan J. P. , Brunger M. J. , Tanaka H.
Published: June 2013

Differential, integral, and momentum transfer cross sections have been determined for the elastic scattering of electrons from the molecules CF3Cl, CF2Cl2, and CFCl3.With the help of a crossed electron beam–molecular beam apparatus using the relative flow technique, the ratios of the elastic differential cross sections (DCSs) of CF3Cl, CF2Cl2, and CFCl3 to those of He were measured in the energy region from 1.5 to 100 eV and at scattering angles in the range 15° to 130°. From those ratios, the absolute DCSs were determined by utilizing the known DCS of He. For CF3Cl and CF2Cl2, at the common energies of measurement, we find generally good agreement with the results from the independent experiments of Mann and Linder [J. Phys. B 25, 1621 (1992)10.1088/0953-4075/25/7/030; Mann and Linder J. Phys. B 25, 1633 (1992)10.1088/0953-4075/25/7/031]. In addition, as a result of progressively substituting a Cl-atom, undulations in the angular distributions have been found to vary in a largely systematic manner in going from CF4 to CF3Cl to CF2Cl2 to CFCl3 and to CCl4. These observed features suggest that the elastic scattering process is, in an independently additive manner, dominated by the atomic-Cl atoms of the molecules. The present independent atom method calculation typically supports the experimental evidence, within the screened additivity rule formulation, for each species and for energies greater than about 10–20 eV. Integral elastic and momentum transfer cross sections were also derived from the measured DCSs, and are compared to the other available theoretical and experimental results. The elastic integral cross sections are also evaluated as a part of their contribution to the total cross section.
The effects of halide anions on the dielectric response of potassium halide solutions in visible, UV and far UV region
Authors: Shagieva F. M. , Boinovich L. B.
Published: June 2013

Based on the experimentally measured dispersion of refractive indices, we studied the effects of halide anions on the dielectric response of potassium halide solutions in the visible, UV and far UV regions. It was shown that a specific ion effect according to the Hofmeister series is clearly demonstrated for the visible range of spectra. For the near-, mid-, and far UV ranges of spectra, the specific ion effect essentially depends on solution concentration and temperature. The influence of ions on the behavior of dynamic dielectric permittivity of a solution is discussed on the basis of ion/water and ion/ion electrostatic and electrodynamic interactions and hydration shell structure.
An experimental approach to identify dynamical models of transcriptional regulation in living cells
Authors: Fiore G. , Menolascina F. , di Bernardo M. , di Bernardo D.
Published: June 2013

We describe an innovative experimental approach, and a proof of principle investigation, for the application of System Identification techniques to derive quantitative dynamical models of transcriptional regulation in living cells. Specifically, we constructed an experimental platform for System Identification based on a microfluidic device, a time-lapse microscope, and a set of automated syringes all controlled by a computer. The platform allows delivering a time-varying concentration of any molecule of interest to the cells trapped in the microfluidics device (input) and real-time monitoring of a fluorescent reporter protein (output) at a high sampling rate. We tested this platform on the GAL1 promoter in the yeast Saccharomyces cerevisiae driving expression of a green fluorescent protein (Gfp) fused to the GAL1 gene. We demonstrated that the System Identification platform enables accurate measurements of the input (sugars concentrations in the medium) and output (Gfp fluorescence intensity) signals, thus making it possible to apply System Identification techniques to obtain a quantitative dynamical model of the promoter. We explored and compared linear and nonlinear model structures in order to select the most appropriate to derive a quantitative model of the promoter dynamics. Our platform can be used to quickly obtain quantitative models of eukaryotic promoters, currently a complex and time-consuming process.
High fidelity microelectromechanical system electrodynamic micro-speaker characterization
Authors: Sturtzer E. , Shahosseini I. , Pillonnet G. , Lefeuvre E. , Lemarquand G.
Published: June 2013

This paper deals with the heterogeneous characterization of a microelectromechanical system (MEMS) electrodynamic micro-speaker. This MEMS micro-speaker consists of an optimized silicon structure based on a very light but very stiff membrane. The mobile part is suspended using soft suspension beams, also made of silicon, which enable large out-of-plane displacement. The electromagnetic motor is composed of a micro-assembly permanent ring magnet and of a deposit mobile planar coil fixed on the top of the silicon membrane. Previous publications have presented the MEMS as theoretically able to produce high fidelity and high efficiency over a wide bandwidth. The present study intends to validate the electrical, the mechanical, and the acoustic performance improvements. The characterization of the microfabricated micro-speaker showed that the electric impedance is flat over the entire audio bandwidth. Some results validates the performance improvements in terms of audio quality as compared to state of the art of the MEMS micro-speakers, such as the high out-of-plane membrane displacement over ±400 μm, the 80 dBSPL sound pressure level at 10 cm, the 2% maximal distortion level, and the useful bandwidth from 335 Hz to cutoff frequency.
Temperature scaling behavior of dynamic hysteresis for (K,Na)NbO3 lead-free ferroelectric films
Authors: Li Tao , Wang Genshui , Du Gang , Li Kui , Chen Ying , Zhou Zhiyong , Cao Fei , Dong Xianlin
Published: June 2013

The temperature scaling of the ferroelectric hysteresis was first investigated in (K,Na)NbO3 films grown on SrRuO3/SrTiO3 over a temperature range from 100 K to 340 K. The power-law temperature scaling relations were obtained for ⟨A⟩, Pr, and Ec in the two distinguished temperature regions, separated by T ∼ 245 K. It was observed that ⟨A⟩ and Pr had a similar temperature dependence, compared with Ec. With increasing T, ⟨A⟩ and Pr decreased in the first region, and increased in the second region. While Ec decreased in the whole temperature range, but with different decrease rate in the two temperature regions.
Resonance magnetoelectric effect in radially polarized long cylindrical composite structures
Authors: Wu Gaojian , Zhang Ru , Zhang Li , Zhu Honghu , Zhang Ning
Published: June 2013

We proposed a theoretical model describing frequency response of magnetoelectric (ME) voltage coefficients in long cylindrical piezoelectric-magnetostrictive composite structures. Using constitutive equations of the materials and equation of motion, an expression for the ME voltage coefficient is derived in terms of material parameters characterizing piezoelectric and magnetostrictive phases and as a function of applied ac magnetic field frequency. It is shown that there is a considerable enhancement in ME voltage coefficient in the region of electromechanical resonance. The resonance frequency equation is obtained as a function of material parameters and geometry sizes. The relationship between resonance frequency and resonance ME effect with geometry size under different boundary mechanical conditions is investigated in trilayered and bilayered cylindrical composites using the derived model. This theoretical work is of some significance for designing ME devices and understanding the resonance vibration mode in cylindrical ME composite structures.
High post-annealing stability in [Pt/Co] multilayers
Authors: Young Lee Tae , Su Son Dong , Ho Lim Sang , Lee Seong-Rae
Published: June 2013

The [Pt/Co] multilayers with a very thin Pt layer of 0.2 nm are presented that exhibit strong perpendicular magnetic anisotropy (PMA) even after annealing up to 500 °C. The observed post-annealing stability is in significant contrast to that previously shown for conventional multilayers with a thicker Pt layer than Co, where good PMA properties are obtained in the as-deposited state but they deteriorate significantly at moderate annealing temperatures below ∼300 °C. The reason for the high post-annealing stability is a low level of intermixing during sputtering due to the very thin Pt layer.
A physical model of switching dynamics in tantalum oxide memristive devices
Authors: Mickel Patrick R. , Lohn Andrew J. , Joon Choi Byung , Joshua Yang J. , Zhang Min-Xian , Marinella Matthew J. , James Conrad D. , Stanley Williams R.
Published: June 2013

We present resistive switching model for TaOx memristors, which demonstrates that the radius of a tantalum rich conducting filament is the state variable controlling resistance. The model tracks the flux of individual oxygen ions and permits the derivation and solving of dynamical and static state equations. Model predictions for ON/OFF switching were tested experimentally with TaOx devices and shown to be in close quantitative agreement, including the experimentally observed transition from linear to non-linear conduction between RON and ROFF. This work presents a quantitative model of state variable dynamics in TaOx memristors, with direct comparison to high-speed resistive switching data.
A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra
Authors: Da B. , Sun Y. , Mao S. F. , Zhang Z. M. , Jin H. , Yoshikawa H. , Tanuma S. , Ding Z. J.
Published: June 2013

A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO2 in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.
Collective oxidation behavior of aluminum nanoparticle aggregate
Authors: Shekhar Adarsh , Wang Weiqiang , Clark Richard , Kalia Rajiv K. , Nakano Aiichiro , Vashishta Priya
Published: June 2013

Aggregates of aluminum nanoparticles are good solid fuel due to high flame propagation rates. Multi-million atom molecular dynamics simulations reveal the mechanism underlying higher reaction rate in a chain of aluminum nanoparticles as compared to an isolated nanoparticle. This is due to the penetration of hot atoms from reacting nanoparticles to an adjacent, unreacted nanoparticle, which brings in external heat and initiates exothermic oxidation reactions. The calculated speed of penetration is 54 m/s, which is within the range of experimentally measured flame propagation rates.
Dynamic composition determination in heterogeneous ensembles using angular autocorrelation functions as signatures
Authors: Li Dongsheng , Xu Zhijie , Ahzi Said
Published: June 2013

Signatures of heterogeneous ensembles composed of multiple types of random oriented particles are represented by the angular autocorrelation functions of the systems. These signatures are retrieved by averaging oversampled angular correlation functions calculated from simulated high throughput X-ray diffraction patterns. Using a component signature matrix, the composition of the heterogeneous system will be directly calculated from the signature of the ensemble. Dynamic composition of a heterogeneous ensemble is determined by fluctuation X-ray scattering using the angular autocorrelation functions as signatures.
Manipulation of skyrmions in nanodisks with a current pulse and skyrmion rectifier
Authors: Lin Shi-Zeng , Reichhardt Charles , Saxena Avadh
Published: June 2013

A skyrmion in a nanosized disk of a chiral magnet can be used as a bit of information. To this end, it is desirable to control the creation and removal of a skyrmion only by currents without using external magnetic fields. Here, we propose to create a skyrmion by applying a current pulse to a nanodisk. The skyrmion can be removed from the disk by applying a dc current. We show that the dynamics of the created skyrmion can lead to a rectification effect, in which a dc voltage is generated by the motion of skyrmion in the presence of an ac current.
Living Apart, Losing Sympathy? How Neighbourhood Context Affects Attitudes to Redistribution and to Welfare Recipients
Authors: Bailey Nick , Gannon Maria , Kearns Ade , Livingston Mark , Leyland Alastair H
Published: June 2013

Rising levels of income inequality have been directly linked to rising levels of spatial segregation. In this paper we explore whether rising segregation may in turn erode support for the redistributive policies of the welfare state, further increasing levels of inequality—a form of positive feedback. The role of the neighbourhood has been neglected in attitudes research but, building on both political geography and ‘neighbourhood effects’ literatures, we theorise that neighbourhood context may shape attitudes through the transmission of attitudes directly and through the accumulation of relevant knowledge. We test this through multilevel modelling of data from England on individual attitudes to redistribution in general and to welfare benefit recipients in particular. We show that the individual factors shaping these attitudes are quite different and that the influence of neighbourhood context also varies as a result. The findings support the idea that neighbourhood context shapes attitudes, with the knowledge accumulation mechanism likely to be the more important. Rising spatial segregation would appear to erode support for redistribution but to increase support for welfare recipients—at least in a context where the dominant media discourse presents such a stigmatising image of those on welfare benefits.
The Fractal Analysis of Architecture: Calibrating the Box-Counting Method Using Scaling Coefficient and Grid Disposition Variables
Authors: Ostwald Michael J
Published: June 2013

Since the mid-1990s architectural researchers have used the box-counting method to calculate the fractal dimension of a range of buildings and urban forms. While this approach has been widely adopted, there has been little consistency in how the multiple variables in the method have been applied. Furthermore, despite precedents in the sciences, no attempt has been made in architectural or urban analysis to use these parameters to calibrate or refine the method. In this paper the computational version of the box-counting approach is presented along with its methodological variables. Thereafter, nine mathematical fractals with known dimensions are tested using this method to identify the optimal approach to the scaling coefficient and grid disposition variables. Finally, using these new settings, two classic architectural test cases are reexamined: Robie House and the Villa Savoye.
Reciprocity as Deliberative Capacity: Lessons from a Citizen's Deliberation on Carbon Pricing Mechanisms in Australia
Authors: Lo Alex Y , Alexander Kim S , Proctor Wendy , Ryan Anthony
Published: June 2013

Australia has seen a deep division in opinion in search of a carbon pricing mechanism. While concepts of carbon taxation and emission trading have comparable public support, climate scepticism is infuencing the debates in political and public spheres in downplaying the need for carbon pricing. Public deliberation is a possible engagement option to address the conflict inherent in climate policy preferences. This research explores the way that a deliberative forum involving twenty-four Australians promoted effective communication between participants through which conflict between policy preferences became more tangible. While the forum did not eliminate disagreement in preferences in the choice of carbon pricing mechanisms, participants reached consensus on fundamental principles such as the need for trusted sources of information, trusted governance procedures, and transparent accountability by appropriate institutions. Shared political expectations encouraged dialogue and cooperation in discussions by enhancing reciprocal understanding. Two sceptical participants who originally had strong opinions different from the rest of the group managed to find common ground. Public deliberative forums that are conducive to reciprocal communication are able to provide a mechanism for joint problem-solving processes that are less adversarial and more responsive to the range of people's preferences.