bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational study of copper–gallium disulphide‐based solar cell devices by using CdS and ZnSe buffer layers
Authors: Singh Pravesh , Gautam Ruchita , Sharma Sheetal , Kumari Sarita , Verma Ajay Singh
Published: July 2014

The authors have performed ab‐initio calculations for the structural, electronic, optical, elastic and thermal properties of the copper–gallium disulphide (CuGaS2). The accurate full potential linearised augmented plane wave method was used to find the equilibrium structural parameters and to compute the full elastic tensors. They have reported electronic and optical properties with the recently developed density functional theory of Tran and Blaha. Furthermore, optical features such as dielectric functions, refractive indices, extinction coefficient, optical reflectivity, absorption coefficients and optical conductivities were calculated for photon energies up to 30 eV. The thermodynamical properties such as thermal expansion, heat capacity, Debye temperature, entropy and Grüneisen parameter, bulk modulus and hardness were calculated employing the quasi‐harmonic Debye model at different temperatures (0–1200 K) and pressures (0–8 GPa) and the results are interpreted. Further, CuGaS2 solar cell devices have been modelled; device physics and performance parameters were analysed for CdS and ZnSe buffer layers. Simulation results for CuGaS2 thin layer solar cell show the maximum efficiency (20.5%) with ZnSe as the buffer layer. Most of the investigated parameters are reported for the first time.
Analysis of collaborative spectrum sensing with binary phase shift keying signal power estimation errors
Authors: Cao Ning , Mao Minghe , Chen Yunfei , Long Min
Published: July 2014

Novel iterative and non‐iterative blind estimation methods for binary phase shift keying modulated primary user signal power are proposed using the maximum‐likelihood principle for collaborative spectrum sensing. Using these estimators, the performance of three different existing collaborative spectrum sensing methods is compared under realistic scenarios. The effect of the primary user traffic on these methods is also explored. Numerical results show that, unlike the case of no estimation error as examined in this literature, the performance gains of the weighted linear combining and optimal combining methods over the conventional equal gain combining method decrease or even become negative when there is estimation error. They also show that the proposed blind estimation methods offer an excellent trade‐off between reliability and complexity.
Flexible dual‐diversity wearable wireless node integrated on a dual‐polarised textile patch antenna
Authors: Vanveerdeghem Peter , Van Torre Patrick , Stevens Christiaan , Knockaert Jos , Rogier Hendrik
Published: July 2014

A new textile wearable wireless node, for operation in the 2.45 GHz industrial, scientific and medical (ISM) band, is proposed. It consists of a dual‐polarised textile patch antenna with integrated microcontroller, sensor, memory and transceiver with receive diversity. Integrated into a garment, the flexible unit may serve for fall detection, as well as for patient or rescue‐worker monitoring. Fragile and lossy interconnections are eliminated. They are replaced by very short radiofrequency signal paths in the antenna feed plane, reducing electromagnetic compatibility and signal integrity problems. The compact and flexible module combines sensing and wireless channel monitoring functionality with reliable and energy‐efficient off‐body wireless communication capability, by fully exploiting dual polarisation diversity. By integrating a battery, a fully autonomous and flexible system is obtained. This novel textile wireless node was validated, both in flat and bent state, in the anechoic chamber, assessing the characteristics of the integrated system in free‐space conditions. Moreover, its performance was verified in various real‐world conditions, integrated into a firefighter garment, and used as an autonomous body‐centric measurement device.
Optimal stochastic capacitor placement problem from the reliability and cost views using firefly algorithm
Authors: Kavousi Fard Abdollah , Niknam Taher
Published: July 2014

This study suggests a new stochastic framework based on point estimate method to capture the uncertainty associated with the forecast error of the active and reactive loads and failure rate and repair rate values. The objective functions to be investigated are system interruption frequency index, system average interruption duration index and average energy not supplied. Meanwhile, since the total MW cost is an attractive issue to the power utilities, the active power losses is also considered as an objective function. In order to explore the problem search space globally, a novel self‐adaptive modification method based on firefly algorithm is proposed. The feasibility and effectiveness of the proposed method are examined on the IEEE 34‐bus test system. According to the simulation results, the proposed framework based on capacitor placement problem can improve the reliability of the system effectively.
Compensation method of propagating distance for guided wave
Authors: Liu Xiaofeng , Bo Lin , Luo Hongling , Fu Libin
Published: July 2014

Guided wave has been utilised in various manners for non‐destructive evaluation and testing. The dispersion and attenuation characteristics of guided wave restrict and complicate the accurate estimation of echo propagation distance. The study focuses on how to reduce the estimation error of propagation distance caused by these characteristics. The propagation of guided wave with attenuation and dispersion characteristics is analytically modelled in general cases. The flight‐time compensation technique is developed based on the analytical model of wave propagation and the algorithm of chirplet matching pursuit. Numerical simulations are given to verify the efficacy of the developed compensation method. Finally, this study demonstrates the use of experimentally measured data for echoes identification and propagation distance estimation.
Detection of multi‐occupancy using device‐free passive localisation
Authors: Deak Gabriel , Curran Kevin , Condell Joan , Deak Daniel
Published: July 2014

Indoor device‐free passive localisation (DfPL) technology uses a received signal strength indication (RSSI)‐based method to record variances of a measured signal where a person being tracked is not carrying any electronic device that can be used to estimate the location. The system monitors the changes in the RSSI measurements caused by the presence of a human body in an indoor environment. For example, it is known that the resonance frequency of water is 2.4 GHz and the human body contains >70% water. Thus, the human body attenuates the wireless signal reacting as an absorber. Wireless communication signal strengths between a number of nodes, using IEEE 802.11 or 802.15.4 standards, show that communication links covering distinct areas cannot be affected simultaneously by only one person. Thus, the authors have deployed a novel system that can identify multi‐occupants in an environment using patterns of motion from those monitored areas. A pattern recognition neural network was used to identify two people in the environment. No other work based on the DfPL technique has focused on multi‐occupancy.
Power control strategy for clustering wireless sensor networks based on multi‐packet reception
Authors: Hu Songhua , Han Jianghong
Published: July 2014

For the requirements of energy saving in wireless sensor networks (WSNs), this study proposes a transmission power control strategy for cluster heads (CHs) based on multi‐packet reception in clustering WSNs. First, this study proposes a new CHs selection algorithm for clustering WSNs. Second, transmission power levels of each CH are determined according to the number of CHs in monitoring area. Third, with restrictions of successive interference cancellation algorithm in sink, transmission power control strategy for CHs are determined by distance from CHs to sink and residual energy of CHs. For whole network, single‐hop communication mode is designed to send data from sensor nodes to CHs, at the same time; it is also applied to send data from CHs to sink. Simulation results show that this power control strategy can reduce the energy consumption of sensor nodes and increase network throughput, which can greatly improve network lifetime. The authors believe that their findings will be useful guidelines for moving forward with successive interference cancellation research in WSNs.
Study on the analysis of gaseous products from lignite steam gasification with waste catalysts
Authors: Lee So Jung , Seo Seok Jin , Sohn Jung Min
Published: July 2014

We performed the steam gasification of lignite char physically mixed with three kinds of waste catalysts obtained from the hydrotreating process of petroleum plants. Steam gasification of lignite char with waste catalysts and K2CO3 was investigated on a fixed bed reactor with gas chromatography and a gas analyzer at the temperature range of 800–900 °C. The gasification reaction rate, carbon conversion and the maximum release rate of major gases increased with increasing gasification temperature. The carbon conversions of the lignite char with waste catalysts were more than 90% and similar to K2CO3. The higher reaction index of lignite char and the largest H2 gross production, 203.3 mmol/gc, was observed with the waste catalyst III. Waste catalysts could be alternatives of K2CO3 for the H2 production from steam lignite gasification.
Combine umbrella sampling with integrated tempering method for efficient and accurate calculation of free energy changes of complex energy surface
Authors: Yang Mingjun , Yang Lijiang , Gao Yiqin , Hu Hao
Published: July 2014

Umbrella sampling is an efficient method for the calculation of free energy changes of a system along well-defined reaction coordinates. However, when there exist multiple parallel channels along the reaction coordinate or hidden barriers in directions perpendicular to the reaction coordinate, it is difficult for conventional umbrella sampling to reach convergent sampling within limited simulation time. Here, we propose an approach to combine umbrella sampling with the integrated tempering sampling method. The umbrella sampling method is applied to chemically more relevant degrees of freedom that possess significant barriers. The integrated tempering sampling method is used to facilitate the sampling of other degrees of freedom which may possess statistically non-negligible barriers. The combined method is applied to two model systems, butane and ACE-NME molecules, and shows significantly improved sampling efficiencies as compared to standalone conventional umbrella sampling or integrated tempering sampling approaches. Further analyses suggest that the enhanced performance of the new method come from the complemented advantages of umbrella sampling with a well-defined reaction coordinate and integrated tempering sampling in orthogonal space. Therefore, the combined approach could be useful in the simulation of biomolecular processes, which often involves sampling of complex rugged energy landscapes.
Structural, magnetic, and electronic properties of iron selenide Fe6-7Se8 nanoparticles obtained by thermal decomposition in high-temperature organic solvents
Authors: Lyubutin I. S. , Lin Chun-Rong , Funtov K. O. , Dmitrieva T. V. , Starchikov S. S. , Siao Yu-Jhan , Chen Mei-Li
Published: July 2014

Iron selenide nanoparticles with the NiAs-like crystal structure were synthesized by thermal decomposition of iron chloride and selenium powder in a high-temperature organic solvent. Depending on the time of the compound processing at 340 °C, the nanocrystals with monoclinic (M)-Fe3Se4 or hexagonal (H)-Fe7Se8 structures as well as a mixture of these two phases can be obtained. The magnetic behavior of the monoclinic and hexagonal phases is very different. The applied-field and temperature dependences of magnetization reveal a complicated transformation between ferrimagnetic (FRM) and antiferromagnetic (AFM) structures, which can be related to the spin rotation process connected with the redistribution of cation vacancies. From XRD and Mössbauer data, the 3c type superstructure of vacancy ordering was found in the hexagonal Fe7Se8. Redistribution of vacancies in Fe7Se8 from random to ordered leads to the transformation of the magnetic structure from FRM to AFM. The Mössbauer data indicate that vacancies in the monoclinic Fe3Se4 prefer to appear near the Fe3+ ions and stimulate the magnetic transition with the rotation of the Fe3+ magnetic moments. Unusually high coercive force Hc was found in both (H) and (M) nanocrystals with the highest (“giant”) value of about 25 kOe in monoclinic Fe3Se4. This is explained by the strong surface magnetic anisotropy which is essentially larger than the core anisotropy. Such a large coercivity is rare for materials without rare earth or noble metal elements, and the Fe3Se4-based compounds can be the low-cost, nontoxic alternative materials for advanced magnets. In addition, an unusual effect of “switching” of magnetization in a field of 10 kOe was found in the Fe3Se4 nanoparticles below 280 K, which can be important for applications.
Bias current ramp rate dependence of the crossover temperature from Kramers to phase diffusion switching in moderately damped NbN/AlN/NbN Josephson junctions
Authors: Lisitskiy M. , Massarotti D. , Galletti L. , Longobardi L. , Rotoli G. , Russo M. , Tafuri F. , Ruggiero B.
Published: July 2014

We investigate the phase dynamics of moderately damped NbN/AlN/NbN Josephson junctions and we present experimental results on detailed aspects of phase diffusion processes. We measure both single escape and multiple escape and retrapping events obtaining a crossover temperature T* from Kramers to phase diffusion switching. We observe a clear dependence of the crossover temperature T* by the bias current ramp rate, while the damping factor Q remains the same. The measured effect is in strong agreement with theoretical predictions reported by Fenton and Warburton.
A compact low-temperature single crystal adsorption calorimetry setup for measuring coverage dependent heats of adsorption at cryogenic temperatures
Authors: Hörtz Peter , Schäfer Rolf
Published: July 2014

Here we present the modification of an already existing Single Crystal Adsorption Calorimetry (SCAC) apparatus which has been extended by a compact cooling system to measure the coverage dependent heats of adsorption of gaseous compounds on thin metal substrates in a temperature range from 80 K to 430 K. The setup is characterized and its performance is tested by studying the adsorption of CO on Pt(111) at 150 K and 300 K. Coverage dependent sticking probabilities and heat of adsorption measurements are compared to previous experimental and theoretical studies proving the reliability of our compact low-temperature-SCAC setup.
A squeeze-like operator approach to position-dependent mass in quantum mechanics
Authors: Moya-Cessa Héctor M. , Soto-Eguibar Francisco , Christodoulides Demetrios N.
Published: July 2014

We provide a squeeze-like transformation that allows one to remove a position dependent mass from the Hamiltonian. Methods to solve the Schrödinger equation may then be applied to find the respective eigenvalues and eigenfunctions. As an example, we consider a position-dependent-mass that leads to the integrable Morse potential and therefore to well-known solutions.
Joint moments of proper delay times
Authors: Martínez-Argüello Angel M. , Martínez-Mares Moisés , García Julio C.
Published: July 2014

We calculate negative moments of the N-dimensional Laguerre distribution for the orthogonal, unitary, and symplectic symmetries. These moments correspond to those of the proper delay times, which are needed to determine the statistical fluctuations of several transport properties through classically chaotic cavities, like quantum dots and microwave cavities with ideal coupling.
Structural and electronic properties of cubic boron nitride doped with zinc
Authors: Li Yubo , Cheng Tianyuan , Wang Xiao , Jiang Huaxing , Yang Hangsheng , Nose Kenji
Published: July 2014

Structural and electronic properties of Zn-doped cubic boron nitride (cBN) were investigated via first principle calculation based on density functional theory. Our simulation suggests that Zn can substitute for both B (ZnB) and N (ZnN) atom; ZnB is energetically favorable, and ZnN can only be prepared under B-rich conditions. ZnB induced a shallow acceptor level; however, the large difference in electronegativity between Zn and N makes the acceptor level strongly localized, which reduces effective carrier density. In the case of ZnN, both deep acceptor levels within band gap and shallow acceptor levels at the top of valence band were induced, which produced more free carriers than ZnB. The calculated results account for experimental results of enhanced electric conductivity of Zn-doped cBN films prepared under B-rich conditions.
A single-molecule approach to ZnO defect studies: Single photons and single defects
Authors: Jungwirth N. R. , Pai Y. Y. , Chang H. S. , MacQuarrie E. R. , Nguyen K. X. , Fuchs G. D.
Published: July 2014

Investigations that probe defects one at a time offer a unique opportunity to observe properties and dynamics that are washed out of ensemble measurements. Here, we present confocal fluorescence measurements of individual defects in ZnO nanoparticles and sputtered films that are excited with sub-bandgap energy light. Photon correlation measurements yield both antibunching and bunching, indicative of single-photon emission from isolated defects that possess a metastable shelving state. The single-photon emission is in the range of ∼560–720 nm and typically exhibits two broad spectral peaks separated by ∼150 meV. The excited state lifetimes range from 1 to 13 ns, consistent with the finite-size and surface effects of nanoparticles and small grains. We also observe discrete jumps in the fluorescence intensity between a bright state and a dark state. The dwell times in each state are exponentially distributed and the average dwell time in the bright (dark) state does (may) depend on the power of the exciting laser. Taken together, our measurements demonstrate the utility of a single-molecule approach to semiconductor defect studies and highlight ZnO as a potential host material for single-defect based applications.
Effect of the wire width on the intrinsic detection efficiency of superconducting-nanowire single-photon detectors
Authors: Lusche R. , Semenov A. , Ilin K. , Siegel M. , Korneeva Y. , Trifonov A. , Korneev A. , Goltsman G. , Vodolazov D. , Hübers H.-W.
Published: July 2014

A thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths has been performed. The experiment shows that the cut-off of the intrinsic detection efficiency at near-infrared wavelengths is most likely controlled by the local suppression of the barrier for vortex nucleation around the absorption site. Beyond the cut-off quasi-particle diffusion in combination with spontaneous, thermally activated vortex crossing explains the detection process. For both materials, the reciprocal cut-off wavelength scales linearly with the wire width where the scaling factor agrees with the hot-spot detection model.
Reversal pathway dependent asymmetric recovery effect in polycrystalline FeNi/FeMn bilayers
Authors: Yang M. , Rui W. B. , Bai X. J. , Zhang X. H. , Liu S. J. , He M. C. , You B. , Du J. , Sun L.
Published: July 2014

For the exchange biased polycrystalline FeNi/FeMn bilayers, we systematically studied the ferromagnet (FM) magnetization reversal pathway dependent recovery effect of training using a vector vibrating sample magnetometer. Our experimental results show unambiguously that the well-known recovery effect strongly depends on the FM magnetization reversal pathway in addition to the final FM magnetization orientation. If the FM magnetization rotates in two opposite directions, i.e., clockwise (CW) or counter clockwise (CCW), to the same final FM magnetization orientation, the recovery effect exhibits distinct asymmetry. For the present initial magnetization configuration, only the CW pathway induces recovery effect, whereas it is impossible to produce training recovery through the CCW pathway. This recovery asymmetry can be explained by considering the random distribution of antiferromagnetic grains' easy axes and the FM magnetization reversal history as well.
Strong photonic crystal behavior in regular arrays of core-shell and quantum disc InGaN/GaN nanorod light-emitting diodes
Authors: Lewins C. J. , Le Boulbar E. D. , Lis S. M. , Edwards P. R. , Martin R. W. , Shields P. A. , Allsopp D. W. E.
Published: July 2014

We show that arrays of emissive nanorod structures can exhibit strong photonic crystal behavior, via observations of the far-field luminescence from core-shell and quantum disc InGaN/GaN nanorods. The conditions needed for the formation of directional Bloch modes characteristic of strong photonic behavior are found to depend critically upon the vertical shape of the nanorod sidewalls. Index guiding by a region of lower volume-averaged refractive index near the base of the nanorods creates a quasi-suspended photonic crystal slab at the top of the nanorods which supports Bloch modes. Only diffractive behavior could be observed without this region. Slab waveguide modelling of the vertical structure shows that the behavioral regime of the emissive nanorod arrays depends strongly upon the optical coupling between the nanorod region and the planar layers below. The controlled crossover between the two regimes of photonic crystal operation enables the design of photonic nanorod structures formed on planar substrates that exploit either behavior depending on device requirements.
Communication: Analysing kinetic transition networks for rare events
Authors: Stevenson Jacob D. , Wales David J.
Published: July 2014

The graph transformation approach is a recently proposed method for computing mean first passage times, rates, and committor probabilities for kinetic transition networks. Here we compare the performance to existing linear algebra methods, focusing on large, sparse networks. We show that graph transformation provides a much more robust framework, succeeding when numerical precision issues cause the other methods to fail completely. These are precisely the situations that correspond to rare event dynamics for which the graph transformation was introduced.
Alumina nanoparticle/polymer nanocomposite dielectric for flexible amorphous indium-gallium-zinc oxide thin film transistors on plastic substrate with superior stability
Authors: Lai Hsin-Cheng , Pei Zingway , Jian Jyun-Ruri , Tzeng Bo-Jie
Published: July 2014

In this study, the Al2O3 nanoparticles were incorporated into polymer as a nono-composite dielectric for used in a flexible amorphous Indium-Gallium-Zinc Oxide (a-IGZO) thin-film transistor (TFT) on a polyethylene naphthalate substrate by solution process. The process temperature was well below 100 °C. The a-IGZO TFT exhibit a mobility of 5.13 cm2/V s on the flexible substrate. After bending at a radius of 4 mm (strain = 1.56%) for more than 100 times, the performance of this a-IGZO TFT was nearly unchanged. In addition, the electrical characteristics are less altered after positive gate bias stress at 10 V for 1500 s. Thus, this technology is suitable for use in flexible displays.
Path of the current flow at the metal contacts of graphene field-effect transistors with distorted transfer characteristics
Authors: Nouchi Ryo , Tanigaki Katsumi
Published: July 2014

Graphene field-effect transistors with source/drain contacts made of metals that can be easily oxidized such as ferromagnetic metals often display a double dip structure in the transfer characteristics because of charge density depinning at the contacts. Generally, transfer characteristics of field-effect transistors show no dependence on the length of the source/drain contacts because charge carrier injection occurs mainly at the edges of the contact. However, the shape of the transfer characteristics of devices fabricated using Ni contacts is found to be dependent on the length of the contact. This peculiar behavior was attributed to charge carrier injection from near the center of the contacts. This is because of oxygen diffusion and the resultant formation of an interfacial oxide layer of non-uniform thickness. The observed contact length dependent transfer characteristics were reproduced using a model calculation that includes charge carrier injection from the center of the electrode and subsequent charge transport underneath the metal contact.
Light-controlled resistive switching of ZnWO4 nanowires array
Authors: Zhao W. X. , Sun B. , Liu Y. H. , Wei L. J. , Li H. W. , Chen P.
Published: July 2014

ZnWO4 nanowires array was prepared on the titanium substrate by a facile hydrothermal synthesis, in which the average length of ZnWO4 nanowires is about 2um and the diameter of individual ZnWO4 nanowire ranges from 50 to 70 nm. The bipolar resistive switching effect of ZnWO4 nanowires array was observed. Moreover, the performance of the resistive switching device is greatly improved under white light irradiation compared with that in the dark.
Antiferromagnetic exchange spring as the reason of exchange bias training effect
Authors: Dobrynin A. N. , Maccherozzi F. , Dhesi S. S. , Fan R. , Bencok P. , Steadman P.
Published: July 2014

We observe recovery of the exchange bias training effect in a Co/CoO bilayer after warming the sample up to the blocking temperature and cooling it back to a low measuring temperature in zero magnetic field. Variation of the magnitude of X-ray magnetic linear dichroism in the sample for the system in the high unidirectional anisotropy state (after field cooling) and in the low unidirectional anisotropy state (after training) suggests rearrangement of antiferromagnetic structure during the initial field cycling in exchange biased state. Our results suggest formation of an antiferromagnetic exchange spring at the frustrated ferromagnetic–antiferromagnetic interface being the reason of the training effect.
Triangular Halogen Bond and Hydrogen Bond Supramolecular Complex Consisting of Carbon Tetrabromide, Halide, and Solvent Molecule: A Theoretical and Spectroscopic Study
Authors: Wu Yu-jie , Zhao Xiao-ran , Gao Hai-yue , Jin Wei-jun
Published: July 2014

The theoretical calculation and spectroscopic experiments indicate a kind of triangular three bonding supramolecular complexes CBr4…X−…H-C, which consist of carbon tetrabromide, halide, and protic solvent molecule (referring to dichloromethane, chloroform and acetonitrile), can be formed in solution. The strength of halogen and hydrogen bonds in the triangular complexes using halide as common acceptor obeys the order of iodide>bromide>chloride. The halogen and hydrogen bonds work weak-cooperatively. Charge transfer bands of halogen bonding complexes between CBr4 and halide are observed in UV-Vis absorption spectroscopy in three solvents, and then the stoichiometry of 1:1, formation constants K and molar extinction coefficients ε of the halogen bonding complexes are obtained by Benesi-Hildebrand method. The K and ε show a dependence on the solvent dielectric constant and, on the whole, obey an order of iodide>bromide>chloride in the same solvents. Furthermore, the C-H vibrational frequencies of solvent molecules vary obviously with the addition of halide, which indicates the C-H…X− interaction. The experimental data indicate that the halogen bond and hydrogen bond coexist by sharing a common halide acceptor as predicted by calculation.
Density Functional Theory Study on Spin States of LaCoO3 at Room Temperature
Authors: Zhang Xiang-bo , Gang Fu , Wan Hui-lin
Published: July 2014

The electronic structure of the perovskite LaCoO3 at room temperature structure (293 K) was calculated by using PBE, PBE+U and HSE. Different spin configurations have been considered. Our calculations showed that the choice of the Hubbard U parameter in DFT+U and mixing factor α in HSE significantly influenced the band gap as well as relative energies. For the spin exited states, the optimal value for U and α were 3.0 eV and 0.05, respectively. Our calculation also emphasized that when U≥5.0 eV, PBE+U would lead to unreasonable electronic structure and energy order.
Morphologies of Core-Shell-Cylinder-Forming ABC Star Triblock Copolymers in Nanopores
Authors: Jiang Wen-bo , Lang Wen-chang , Li Shi-ben , Wang Xiang-hong
Published: July 2014

The self-assembly behavior of ABC star triblock copolymers can lead to a large number of nanostructures. Indeed, many new and interesting structures have already been discovered and proven to be hotspot in soft matter physics research. In this work, we introduce different phase diagrams of core-shell-cylinder-forming ABC star triblock copolymers under different conditions, including in-bulk and pore geometries with different sizes. The relation between the pore size geometries and their corresponding structures are also revealed. The different properties of the surface potential field that significantly affect the self-assembly process of ABC star triblock copolymers are investigated as well.
Contrast Response Functions with Wide-View Stimuli in the Human Visual Cortex
Authors: Yan Tianyi , Wang Bin , Geng Yansong , Yan Yaqi , Mu Nan , Wu Jinglong , Guo Qiyong , Tang Xiaoying , Zeng Yanjun , Peng Yuhua
Published: July 2014

In this manuscript, using a novel wide-view visual presentation system that we developed for vision research and functional magnetic resonance imaging (fMRI), we studied contrast response functions in regions of the brain that are central and peripheral to the entire set of visual areas (V1, V2, V3, V3A, MT+), regions that have not been all investigated in previous vision research. Under the stimulus conditions which were 0–20 deg, 20–40 deg, and 40–60 deg eccentricity black-and-white checkerboard patterns, we measured the blood oxygenation level-dependent fMRI contrast response at five contrast levels (6, 12, 24, 48, and 96%) in the visual areas. On the basis of these data, the central and pericentral visual areas had low-contrast gain, whereas the peripheral visual areas had high-contrast gain. In addition, our results showed that the signals fundamentally shift during visual processing through posterior visual cortical areas (V1, V2, and V3) to superior visual cortical areas (V3A and MT+).
Decreasing methane emissions from ruminants grazing forages: a fit with productive and financial realities?
Authors: Pacheco David , Waghorn Garry , Janssen Peter H.
Published: July 2014

Ruminants contribute to human food supply and also anthropogenic greenhouse gas (GHG) emissions. An understanding of production systems and information on animal populations has enabled global inventories of ruminant GHG emissions (methane and nitrous oxide), and dietary strategies are being developed to reduce GHG emissions from ruminants. Mitigation strategies need to consider the management/feeding systems used to ensure that these strategies will be readily accepted and adopted by farmers. Housed systems allow diets to be formulated in ways that may reduce GHG production, but the challenge is much greater for systems where animals graze outdoors for long periods. A methane mitigation option in the form of fresh forage would be desirable in livestock production systems with high reliance on grazing. A brief summary of New Zealand research, carried out on fresh grasses, legumes, herbs and crops, suggest that we have an incomplete understanding of the feed characteristics that define a ‘high’ or a ‘low’ methane feed. The variation in methane emissions measured between feeds, individual animals and experiment is large, even in controlled conditions, and the dynamic nature of sward-animal interactions will only exacerbate this variation, creating challenges beyond the identification of mitigants. Furthermore, implementation of knowledge gained from controlled studies requires validation under grazing systems to identify any trade-offs between methane reduction and animal productivity or emission of other pollutants. Therefore, investment and research should be targeted at mitigation options that can and will be adopted on-farm, and the characteristics of temperate grasslands farming suggest that these options may differ from those for intensive (high input/output) or extensive (low input/output) systems.
Development of an Antibiotic Spectrum Score Based on Veterans Affairs Culture and Susceptibility Data for the Purpose of Measuring Antibiotic De-Escalation: A Modified Delphi Approach
Authors: Madaras-Kelly Karl , Jones Makoto , Remington Richard , Hill Nicole , Huttner Benedikt , Samore Matthew
Published: July 2014

Objective

Development of a numerical score to measure the microbial spectrum of antibiotic regimens (spectrum score) and method to identify antibiotic de-escalation events based on application of the score.

Design

Web-based modified Delphi method.

Participants.

Physician and pharmacist antimicrobial stewards practicing in the United States recruited through infectious diseases–focused listservs.

Methods

Three Delphi rounds investigated: organisms and antibiotics to include in the spectrum score, operationalization of rules for the score, and de-escalation measurement. A 4-point ordinal scale was used to score antibiotic susceptibility for organism-antibiotic domain pairs. Antibiotic regimen scores, which represented combined activity of antibiotics in a regimen across all organism domains, were used to compare antibiotic spectrum administered early (day 2) and later (day 4) in therapy. Changes in spectrum score were calculated and compared with Delphi participants’ judgments on de-escalation with 20 antibiotic regimen vignettes and with non-Delphi steward judgments on de-escalation of 300 pneumonia regimen vignettes. Method sensitivity and specificity to predict expert de-escalation status were calculated.

Results

Twenty-four participants completed all Delphi rounds. Expert support for concepts utilized in metric development was identified. For vignettes presented in the Delphi, the sign of change in score correctly classified de-escalation in all vignettes except those involving substitution of oral antibiotics. The sensitivity and specificity of the method to identify de-escalation events as judged by non-Delphi stewards were 86.3% and 96.0%, respectively.

Conclusions

Identification of de-escalation events based on an algorithm that measures microbial spectrum of antibiotic regimens generally agreed with steward judgments of de-escalation status.

Infect Control Hosp Epidemiol 2014;35(9):1103-1113
The Association of State Legal Mandates for Data Submission of Central Line–Associated Bloodstream Infections in Neonatal Intensive Care Units with Process and Outcome Measures
Authors: Zachariah Philip , Reagan Julie , Furuya E. Yoko , Dick Andrew , Liu Hangsheng , Herzig Carolyn T. A. , Pogorzelska-Maziarz Monika , Stone Patricia W. , Saiman Lisa
Published: July 2014

Objective

To determine the association between state legal mandates for data submission of central line–associated bloodstream infections (CLABSIs) in neonatal intensive care units (NICUs) with process and outcome measures.

Design

Cross-sectional study.

Participants. National sample of level II/III and III NICUs participating in National Healthcare Safety Network (NHSN) surveillance.

Methods

State mandates for data submission of CLABSIs in NICUs in place by 2011 were compiled and verified with state healthcare-associated infection coordinators. A web-based survey of infection control departments in October 2011 assessed CLABSI prevention practices, ie, compliance with checklist/bundle components (process measures) in ICUs including NICUs. Corresponding 2011 NHSN NICU CLABSI rates (outcome measures) were used to calculate standardized infection ratios (SIRs). Association between mandates and process and outcome measures was assessed by multivariable logistic regression.

Results

Among 190 study NICUs, 107 (56.3%) were located in states with mandates, with mandates in place >3 years in 52 (49%). More NICUs in states with mandates reported ≥95% compliance to at least 1 CLABSI prevention practice (52.3%–66.4%) than NICUs in states without mandates (28.9%–48.2%). Mandates were predictors of ≥95% compliance with all practices (odds ratio, 2.8; 95% confidence interval, 1.4–6.1). NICUs in states with mandates reported lower mean CLABSI rates in the ≤750-g birth weight group (2.4 vs 5.7 CLABSIs/1,000 central line–days) but not in others. Mandates were not associated with SIR <1.

Conclusions

State mandates for NICU CLABSI data submission were significantly associated with ≥95% compliance with CLABSI prevention practices, which declined with the duration of mandate but not with lower CLABSI rates.

Infect Control Hosp Epidemiol 2014;35(9):1133-1139
Linear independence of Poincaré series of exponential type via non-analytic methods
Authors: Böcherer Siegfried , Das Soumya
Published: July 2014

Given a finite set

{
T
}

\{T\}

of symmetric, positive definite, half-integral

n
n

by

n
n

matrices over

Z

\mathbf {Z}

which are inequivalent under the action of

G
L

(
n
,

Z

)

\mathrm {GL}(n, \mathbf {Z})

, we show that the corresponding set of Poincaré series

{

P
k
n

(
T
)
}

\{ P_k^n(T) \}

attached to them are linearly independent for weights

k
k

in infinitely many arithmetic progressions. We also give a quite explicit description of those arithmetic progressions for all even degrees, when the matrices

T
T

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Map the Meal Gap: Exploring Food Insecurity at the Local Level
Authors: Gundersen Craig , Engelhard Emily , Waxman Elaine
Published: July 2014

The burgeoning food insecurity literature in the United States has provided a portrait of the causes and consequences of food insecurity. One underexplored aspect is the spatial diversity in food insecurity across the United States. In response, Feeding America has been releasing annual county‐level food insecurity estimates since 2010. In this article, we describe the methods underlying these estimates, followed by answers to the following: What are the state‐level determinants of food insecurity? What is the distribution of food insecurity across counties in the United States? How do the county‐level food insecurity estimates generated in Map the Meal Gap compare with other sources?
Futures Prices in Supply Analysis: Are Instrumental Variables Necessary?
Authors: Hendricks Nathan P. , Janzen Joseph P. , Smith Aaron
Published: July 2014

Crop yield shocks are partially predictable—high planting‐time futures prices have tended to indicate that yield would be below trend. As a result, regressions of total caloric production on futures prices produce estimates of the supply elasticity that are biased downwards by up to 75%. Regressions of the world's growing area on futures prices have a much smaller bias of about 20% because although yield shocks are partially predictable, this predictability has a relatively small effect on land allocation. We argue that the preferred method for estimating the crop supply elasticity is to use regressions of growing area on futures prices and to include the realized yield shock as a control variable. An alternative method for bias reduction is to use instrumental variables (IVs). We show that the marginal contribution of an IV to bias reduction is small—IVs are not necessary for futures prices in supply analysis.
Más-o-menos: a simple sign averaging method for discrimination in genomic data analysis
Authors: Zhao Sihai Dave , Parmigiani Giovanni , Huttenhower Curtis , Waldron Levi
Published: July 2014

Motivation : The successful translation of genomic signatures into clinical settings relies on good discrimination between patient subgroups. Many sophisticated algorithms have been proposed in the statistics and machine learning literature, but in practice simpler algorithms are often used. However, few simple algorithms have been formally described or systematically investigated.

Results : We give a precise definition of a popular simple method we refer to as más-o-menos, which calculates prognostic scores for discrimination by summing standardized predictors, weighted by the signs of their marginal associations with the outcome. We study its behavior theoretically, in simulations and in an extensive analysis of 27 independent gene expression studies of bladder, breast and ovarian cancer, altogether totaling 3833 patients with survival outcomes. We find that despite its simplicity, más-o-menos can achieve good discrimination performance. It performs no worse, and sometimes better, than popular and much more CPU-intensive methods for discrimination, including lasso and ridge regression.

Availability and Implementation : Más-o-menos is implemented for survival analysis as an option in the survHD package, available from http://www.bitbucket.org/lwaldron/survhd and submitted to Bioconductor.

Contact : sdzhao@illinois.edu
Predicting protein phosphorylation from gene expression: top methods from the IMPROVER Species Translation Challenge
Authors: Dayarian Adel , Romero Roberto , Wang Zhiming , Biehl Michael , Bilal Erhan , Hormoz Sahand , Meyer Pablo , Norel Raquel , Rhrissorrakrai Kahn , Bhanot Gyan , Luo Feng , Tarca Adi L.
Published: July 2014

Motivation: Using gene expression to infer changes in protein phosphorylation levels induced in cells by various stimuli is an outstanding problem. The intra-species protein phosphorylation challenge organized by the IMPROVER consortium provided the framework to identify the best approaches to address this issue.

Results: Rat lung epithelial cells were treated with 52 stimuli, and gene expression and phosphorylation levels were measured. Competing teams used gene expression data from 26 stimuli to develop protein phosphorylation prediction models and were ranked based on prediction performance for the remaining 26 stimuli. Three teams were tied in first place in this challenge achieving a balanced accuracy of about 70%, indicating that gene expression is only moderately predictive of protein phosphorylation. In spite of the similar performance, the approaches used by these three teams, described in detail in this article, were different, with the average number of predictor genes per phosphoprotein used by the teams ranging from 3 to 124. However, a significant overlap of gene signatures between teams was observed for the majority of the proteins considered, while Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were enriched in the union of the predictor genes of the three teams for multiple proteins.

Availability and implementation: Gene expression and protein phosphorylation data are available from ArrayExpress (E-MTAB-2091). Software implementation of the approach of Teams 49 and 75 are available at http://bioinformaticsprb.med.wayne.edu and http://people.cs.clemson.edu/∼luofeng/sbv.rar, respectively.

Contact: gyanbhanot@gmail.com or luofeng@clemson.edu or atarca@med.wayne.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
STAMP: statistical analysis of taxonomic and functional profiles
Authors: Parks Donovan H. , Tyson Gene W. , Hugenholtz Philip , Beiko Robert G.
Published: July 2014

Summary: STAMP is a graphical software package that provides statistical hypothesis tests and exploratory plots for analysing taxonomic and functional profiles. It supports tests for comparing pairs of samples or samples organized into two or more treatment groups. Effect sizes and confidence intervals are provided to allow critical assessment of the biological relevancy of test results. A user-friendly graphical interface permits easy exploration of statistical results and generation of publication-quality plots.

Availability and implementation: STAMP is licensed under the GNU GPL. Python source code and binaries are available from our website at: http://kiwi.cs.dal.ca/Software/STAMP

Contact:  donovan.parks@gmail.com

Supplementary information:  Supplementary data are available at Bioinformatics online.
EU Competition Law
Authors: Jones Alison , Sufrin Brenda
Published: July 2014

All books in this flagship series contain carefully selected substantial extracts from key cases, legislation, and academic debate, providing able students with a stand-alone resource. EU Competition Law: Text, Cases, and Materials provides a complete guide to European competition law in a single authoritative volume, pairing extract material with clear and in-depth author commentary. Carefully selected extracts from key cases, academic articles, and statutory materials are accompanied by in-depth commentary and critique from two experienced academics in the field. Thorough footnoting and referencing give a tour of the available literature, making this an ideal text for undergraduate and postgraduate students, as well as competition law scholars engaged in specialized study. This fifth edition has been fully updated with: detailed coverage and commentary on judgments, decisions, regulations and other measures published by competition law authorities including the Court of Justice, the European Court of Human Rights, the European Commission, and various national courts; coverage of key Article 101 cases including Expedia , T-Mobile , Pierre Fabre , Allianz Hungária Biztosító Zrt , and Generali-Providencia Biztosító Zrt v. Gazdasági Versenyhivatal ; Article 102 cases, including TeliaSonera , Deutsche Telekom , Telefónica , Tomra , Post Danmark , and AstraZeneca ; and thorough discussion of ongoing developments in competition law, including the Commission's aggressive enforcement policy against cartels, the review of merger processes and regulations, the compatibility of EU competition procedures with human rights provisions, and the increased number of Article 267 references from national courts.
Article 101 TFEU: The Elements
Authors: Jones Alison , Sufrin Brenda
Published: July 2014

All books in this flagship series contain carefully selected substantial extracts from key cases, legislation, and academic debate, providing able students with a stand-alone resource. This chapter discusses the text of Article 101; the scheme of Article 101; the interpretation and application of Article 101(1); Article 101(2); and exclusions.
Introduction to Article 102 TFEU
Authors: Jones Alison , Sufrin Brenda
Published: July 2014

All books in this flagship series contain carefully selected substantial extracts from key cases, legislation, and academic debate, providing able students with a stand-alone resource. Article 102 TFEU deals with the unilateral conduct of undertakings with substantial market power and prohibits one or more undertakings which hold a dominant position in the internal market or a substantial part of it abusing that position insofar as it may affect inter-Member State trade. This chapter discusses the text of Article 102; the scheme of Article 102; the interpretation and application of Article 102; and the relationship between Article 102 and Article 101.
Article 102 TFEU: Conduct which can be an Abuse
Authors: Jones Alison , Sufrin Brenda
Published: July 2014

All books in this flagship series contain carefully selected substantial extracts from key cases, legislation, and academic debate, providing able students with a stand-alone resource. This chapter discusses the following: the meaning of ‘abuse’ in Article 102; types of conduct that may constitute an abuse; dominance and abuse in different markets; general issues in respect of abuses concerning prices; predatory pricing; margin squeeze; exclusive purchasing (single branding) contracts, and discount and rebate schemes; tying and bundling; refusal to supply; other exclusionary practices; discrimination contrary to Article 102(c); exploitative abuses; refusal to supply, export bans and other conduct hindering inter-member state trade; and abuse and collective dominance.