bluuebunny/crossref_metadata_2025 huggingface dataset:
Proportional fairness resource allocation scheme based on quantised feedback for multiuser orthogonal frequency division multiplexing system
Authors: Xu Lei , Li Ya‐ping , Yang Yu‐wang , Zhang Xiaofei , Tang Zhen‐min , Lan Shao‐hua
Published: August 2014

This work addresses the resource allocation problem with the proportional fair constraint condition based on quantised feedback for multiuser orthogonal frequency division multiplexing access system. The resource allocation problem is converted as an optimisation problem with maximising the lower bound of the total average throughput and this formulation provides the low complexity of solving the above resource allocation problem. Tailored for the above optimisation problem, the authors design the codebook of equivalent channel quantisation threshold and the codebook of power and rate according to the equal probability quantiser and the Lagrange multiplier method, respectively. Further, they develop a suboptimal algorithm based on the stochastic approximate method. The proposed algorithm not only satisfies the constraint condition of the proportional fair very well, but also reduces the feedback overhead of the resource allocation result greatly. Moreover, the average throughput of the proposed algorithm is very close to that of the optimal resource allocation algorithm with full feedback when the equivalent channel gain in every subcarrier is quantised by 4 bit.
Study on the stability of the topology interactive growth mechanism using graph spectra
Authors: Bo Jiao , Ying Zhou , Jing Du , Cheng‐dong Huang , Zhi‐yong Lu , Ying‐long Liu
Published: August 2014

In terms of spectral graph theory, the graph spectrums represent more accurate structural properties and robust characteristics of the network topologies. In this study, the authors study the stability characteristics of the normalised Laplacian spectrum associated with the interactive growth mechanism for the increasing of nodes in the generation of large‐scale autonomous systems (AS) graphs. With consecutive snapshots of the AS‐level Internet topologies, the authors obtain the stable models of the spectrum. In addition, the authors investigate the stability conditions of the spectrum based on the interactive growth mechanism and the comparisons with other metrics and study how to influence the spectrum by the inputs of the interactive growth mechanism.
Non‐linear disturbance observer‐based back‐stepping control for airbreathing hypersonic vehicles with mismatched disturbances
Authors: Sun Haibin , Li Shihua , Yang Jun , Guo Lei
Published: August 2014

This study concerns with robust tracking control problem for the longitudinal model of airbreathing hypersonic vehicles (AHVs). The AHVs include serious non‐linearities, strong couplings, parametric perturbations and mismatched disturbances, which results in great difficultly in the controller design. By using back‐stepping method and non‐linear disturbance observer technique, a novel composite controller is proposed, which can guarantee system outputs asymptotically track their reference signals. A new idea is that disturbance estimations are introduced into virtual control law in each step to compensate the mismatched disturbances. As compared with other robust flight control methods for AHVs, the developed method exhibits not only excellent robustness and disturbance rejection performance but also the property of nominal performance recovery. Finally, the effectiveness of the proposed method is demonstrated by simulation results.
Mechanism of vehicular periodic operation for optimal fuel economy in free‐driving scenarios
Authors: Li Shengbo Eben , Hu Xiaosong , Li Keqiang , Ahn Changsun
Published: August 2014

In addition to the fuel‐efficient design of vehicles, eco‐driving technologies can further reduce the fuel consumption and carbon emissions of road transportation. One of the major issues in eco‐driving technologies is how to determine the fuel savings or fuel‐optimised operating strategies of the power train. We examine the periodic operation of autonomous vehicles in free‐driving scenarios with the purpose of maximising fuel economy. The design of such strategies can be considered to be an optimal control problem, which is proved by π ‐test to have singular arcs because of the S‐shaped engine fueling rate. The optimal operations are solved numerically by using the Legendre pseudospectral method, and many are found to demonstrate periodic behaviours, that is, pulse and gliding. In periodic operation, the engine switches between the minimum break specific fuel consumption point and the idling point, while the vehicle speed oscillates between its upper and lower bounds. The formation of periodic operation, as well as some key properties, is analysed and presented.
C‐band complementary metal‐oxide‐semiconductor bandpass filter using active capacitance circuit
Authors: Wang Sen , Lin Wen‐Jie
Published: August 2014

In this study, a second‐order Chebyshev active bandpass filter with three finite transmission zeros at C‐Band is presented. This filter utilises an active capacitance technique to compensate resistive losses of resonators, and a shunt‐feedback inductor between input and output to achieve the transmission zeros in the bandpass filter. Moreover, one transmission zero is in the lower stopband, and two transmission zeros are in the upper stopband, thus improving the selectivity of the filter significantly. The filter is designed and fabricated in a standard 0.18 μm CMOS technology with a chip area of 0.92 mm × 0.76 mm including all testing pads. The filter achieves 0.77 dB insertion loss, 18 dB return loss, and 32% 3 dB bandwidth at 5.3 GHz with 2.2 mW power consumption. The measured NF and input P1 dB is 4.3 dB and 2.5 dBm, respectively. Finally, the rejection levels at these transmission zeros are greater than 14.4 dB.
Zeroth‐order resonant circular patch antenna based on periodic structures
Authors: Yan Sen , Vandenbosch Guy A.E.
Published: August 2014

The circular patch antenna loaded with a periodic structure implementing a composite right/left‐handed transmission line (TL) is introduced. The corresponding circuit model of the radial TL is derived to analyse this circular antenna. Since the unit cells of this TL can support arbitrary phase shift, the antenna can form negative modes, positive modes and zeroth‐order resonant (ZOR) modes. For a ZOR antenna, the resonant frequency is independent of its physical size. The resonant frequency, input impedance and radiation characteristics of the ZOR circular antenna are analysed in terms of the physical parameters of the unit cells. Two ZOR circular antennas are designed showing monopolar radiation patterns. One is electrically extremely large, yielding a high directivity, and the other one is electrically small.
W‐band low‐loss bandpass filter using rectangular resonant cavities
Authors: Liao Xiaoyi , Wan Lei , Yin Yong , Zhang Yichi
Published: August 2014

This study shows a high performance of W‐band bandpass filter using a simple structure, which has advantages of low cost and simple process. This filter is composed of four rectangular resonant cavities, which are connected together by series. We designed and optimised the sizes of four cavities and the sizes of coupling holes by Ansoft's High Frequency Structure Simulator 13.0 (HFSS 13.0). The simulation result of the filter shows that it has the centre frequency at 92.62 GHz, 4.07% (3.86 GHz) bandwidth, a 0.4 dB insertion loss in the passband and a 1.51 rectangular coefficient. The measured response of the filter agrees with the simulation result, which has the centre frequency at 92.6 GHz, 4.53% (4.20 GHz) bandwidth, and an average insertion loss less than 0.5 dB in the passband. The rectangular coefficient of test result is 1.61. The simulation result also prove that it is easy to obtain a W‐band bandpass filter which has a centre frequency range from 90 to 100 GHz with a bandwidth ranging from 3 to 9 GHz by slightly adjusting key sizes of the structure, such as chamfer radius and thickness of the iris.
Surface structures of In-Pd intermetallic compounds. II. A theoretical study
Authors: Gaudry É. , McGuirk G. M. , Ledieu J. , Fournée V.
Published: August 2014

The (110) surface of the InPd intermetallic compound and the In–Pd surface alloy properties are investigated in the framework of the density functional theory, within the projector augmented plane-wave method. Surface segregation is calculated to be energetically unfavorable at stoichiometric InPd(110) surfaces, while indium antisites are shown to segregate to the surface in off-stoichiometric InPd(110) systems. Concerning surface alloys obtained by burying In-doped Pd layers in Pd(111), we demonstrated that the most stable ones are those presenting atomic indium concentrations below 50 at. % (11 at. %, 25 at. %, 33 at. %). According to our calculations, the In-doped Pd layers with concentration above or equal to 50% lead to In-doped Pd multilayers, each presenting an atomic indium concentration below 50 at. %. Alloying and segregation effects in InPd intermetallic compound and In–Pd surface alloys clearly agree with the larger bonding strength of In–Pd (−0.44 eV) compared to In–In (−0.29 eV) and Pd–Pd (−0.31 eV).
Cell-matrix adhesion characterization using multiple shear stress zones in single stepwise microchannel
Authors: Kim Min-Ji , Doh Il , Bae Gab-Yong , Cha Hyuk-Jin , Cho Young-Ho
Published: August 2014

This paper presents a cell chip capable to characterize cell-matrix adhesion by monitoring cell detachment rate. The proposed cell chip can supply multiple levels of shear stress in single stepwise microchannel. As epithelial-mesenchymal transition (EMT), one of hallmarks of cancer metastasis is closely associated to the interaction with extracelluar matrix (ECM), we took advantage of two lung cancer cell models with different adhesion properties to ECM depending their epithelial or mesenchymal properties, including the pair of lung cancer cells with (A549sh) or without E-cadherin expression (A549sh-Ecad), which would be optimal model to examine the alteration of adhesion properties after EMT induction. The cell-matrix adhesion resisting to shear stress appeared to be remarkably differed between lung cancer cells. The detachment rate of epithelial-like H358 and mesenchymal-like H460 cells was 53%–80% and 25%–66% in the shear stress range of 34–60 dyn/cm2, respectively. A549sh-Ecad cells exhibits lower detachment rate (5%–9%) compared to A549sh cells (14%–40%). By direct comparison of adhesion between A549sh and A549sh-Ecad, we demonstrated that A549shE-cad to mimic EMT were more favorable to the ECM attachment under the various levels of shear stress. The present method can be applied to quantitative analysis of tumor cell-ECM adhesion.
Alloying and oxidation of in situ produced core-shell Al@Yb nanoalloy particles—An “on-the-fly” study
Authors: Zhang Chaofan , Andersson Tomas , Mikkelä Mikko-Heikki , Mårsell Erik , Björneholm Olle , Xu Xiaojun , Tchaplyguine Maxim , Liu Zejin
Published: August 2014

Core-shell-structured nanoalloy particles with an Al-dominated interior covered by few Yb monolayers have been fabricated using a vapor-aggregation method involving magnetron sputtering. The radially segregated structure of the Yb-Al nanoparticles has been disclosed by “on-the-fly” photoelectron spectroscopy monitoring of the nanoparticle beam in Yb 4f and Al 2p electron binding energy regions. Both, the binding energy values and the electron microscopy images taken on the deposited nanoparticles, allow estimating their dimensions to be in the 5–10 nm range. The photoelectron spectroscopy results suggest that in these nanoparticles no trivalent Yb – the typical case for the macroscopic Yb-Al alloy – is present. The oxidation of preformed Yb-Al nanoparticles was successfully attempted, leading to the appearance of divalent Yb surface oxide – in contrast to the bulk macroscopic Yb which is trivalent in the oxide. Our results suggest that at intermediate oxygen exposures “sandwich-like” nanoparticles of YbO/Yb/Al were synthesized. At higher O2 exposures, the oxygen seems to penetrate all the way to the Yb-Al interface. The results of the present study have to be considered when photonic applications of Yb-doped garnet nanoparticles are planned.
Symmetrical windowing for quantum states in quasi-classical trajectory simulations: Application to electron transfer
Authors: Cotton Stephen J. , Igumenshchev Kirill , Miller William H.
Published: August 2014

It has recently been shown [S. J. Cotton and W. H. Miller, J. Chem. Phys. 139, 234112 (2013)] that a symmetrical windowing quasi-classical (SQC) approach [S. J. Cotton and W. H. Miller, J. Phys. Chem. A 117, 7190 (2013)] applied to the Meyer-Miller model [H.-D. Meyer and W. H. Miller, J. Chem. Phys. 70, 3214 (1979)] for the electronic degrees of freedom in electronically non-adiabatic dynamics is capable of quantitatively reproducing quantum mechanical results for a variety of test applications, including cases where “quantum” coherence effects are significant. Here we apply this same SQC methodology, within a flux-side correlation function framework, to calculate thermal rate constants corresponding to several proposed models of electron transfer processes [P. Huo, T. F. Miller III, and D. F. Coker, J. Chem. Phys. 139, 151103 (2013); A. R. Menzeleev, N. Ananth, and T. F. Miller III, J. Chem. Phys. 135, 074106 (2011)]. Good quantitative agreement with Marcus Theory is obtained over several orders of magnitude variation in non-adiabatic coupling. Moreover, the “inverted regime” in thermal rate constants (with increasing bias) known from Marcus Theory is also reproduced with good accuracy by this very simple classical approach. The SQC treatment is also applied to a recent model of photoinduced proton coupled electron transfer [C. Venkataraman, A. V. Soudackov, and S. Hammes-Schiffer, J. Chem. Phys. 131, 154502 (2009)] and population decay of the photoexcited donor state is found to be in reasonable agreement with results calculated via reduced density matrix theory.
Unextendible product basis for fermionic systems
Authors: Chen Jianxin , Chen Lin , Zeng Bei
Published: August 2014

We discuss the concept of unextendible product basis (UPB) and generalized UPB for fermionic systems, using Slater determinants as an analogue of product states, in the anti-symmetric subspace \documentclass[12pt]{minimal}\begin{document}$\wedge ^ N {\mathbb {C}}^M$\end{document}∧NCM. We construct an explicit example of generalized fermionic unextendible product basis (FUPB) with minimum cardinality N(M − N) + 1 for any N ⩾ 2, M ⩾ 4. We also show that any bipartite anti-symmetric space \documentclass[12pt]{minimal}\begin{document}$\wedge ^ 2 {\mathbb {C}}^M$\end{document}∧2CM of codimension two is spanned by Slater determinants, and the spaces of higher codimension may not be spanned by Slater determinants. Furthermore, we construct an example of complex FUPB of N = 2, M = 4 with minimum cardinality 5. In contrast, we show that a real FUPB does not exist for N = 2, M = 4. Finally, we provide a systematic construction for FUPBs of higher dimensions by using FUPBs and UPBs of lower dimensions.
A new method of measuring the poloidal magnetic and radial electric fields in a tokamak using a laser-accelerated ion-beam trace probe
Authors: Yang X. Y. , Chen Y. H. , Lin C. , Wang L. , Xu M. , Wang X. G. , Xiao C. J.
Published: August 2014

Both the poloidal magnetic field (Bp) and radial electric field (Er) are significant in magnetic confinement devices. In this paper, a new method was proposed to diagnose both Bp and Er at the same time, which was named Laser-accelerated Ion-beam Trace Probe (LITP). This method based on the laser-accelerated ion beam, which has three properties: large energy spread, short pulse lengths, and multiple charge states. LITP can provide the 1D profiles, or 2D images of both Bp and Er. In this paper, we present the basic principle and some preliminary theoretical results.
Role of silicon excess in Er-doped silicon-rich nitride light emitting devices at 1.54 μm
Authors: Ramírez J. M. , Cueff S. , Berencén Y. , Labbé C. , Garrido B.
Published: August 2014

Erbium-doped silicon-rich nitride electroluminescent thin-films emitting at 1.54 μm have been fabricated and integrated within a metal-oxide-semiconductor structure. By gradually varying the stoichiometry of the silicon nitride, we uncover the role of silicon excess on the optoelectronic properties of devices. While the electrical transport is mainly enabled in all cases by Poole-Frenkel conduction, power efficiency and conductivity are strongly altered by the silicon excess content. Specifically, the increase in silicon excess remarkably enhances the conductivity and decreases the charge trapping; however, it also reduces the power efficiency. The main excitation mechanism of Er3+ ions embedded in silicon-rich nitrides is discussed. The optimum Si excess that balances power efficiency, conductivity, and charge trapping density is found to be close to 16%.
Enhancing metal-insulator-insulator-metal tunnel diodes via defect enhanced direct tunneling
Authors: Alimardani Nasir , Conley John F.
Published: August 2014

Metal-insulator-insulator-metal tunnel diodes with dissimilar work function electrodes and nanolaminate Al2O3-Ta2O5 bilayer tunnel barriers deposited by atomic layer deposition are investigated. This combination of high and low electron affinity insulators, each with different dominant conduction mechanisms (tunneling and Frenkel-Poole emission), results in improved low voltage asymmetry and non-linearity of current versus voltage behavior. These improvements are due to defect enhanced direct tunneling in which electrons transport across the Ta2O5 via defect based conduction before tunneling directly through the Al2O3, effectively narrowing the tunnel barrier. Conduction through the device is dominated by tunneling, and operation is relatively insensitive to temperature.
Hydrogen intercalation of single and multiple layer graphene synthesized on Si-terminated SiC(0001) surface
Authors: Sołtys Jakub , Piechota Jacek , Ptasinska Maria , Krukowski Stanisław
Published: August 2014

Ab initio density functional theory simulations were used to investigate the influence of hydrogen intercalation on the electronic properties of single and multiple graphene layers deposited on the SiC(0001) surface (Si-face). It is shown that single carbon layer, known as a buffer layer, covalently bound to the SiC substrate, is liberated after hydrogen intercalation, showing characteristic Dirac cones in the band structure. This is in agreement with the results of angle resolved photoelectron spectroscopy measurements of hydrogen intercalation of SiC-graphene samples. In contrast to that hydrogen intercalation has limited impact on the multiple sheet graphene, deposited on Si-terminated SiC surface. The covalently bound buffer layer is liberated attaining its graphene like structure and dispersion relation typical for multilayer graphene. Nevertheless, before and after intercalation, the four layer graphene preserved the following dispersion relations in the vicinity of K point: linear for (AAAA) stacking, direct parabolic for Bernal (ABAB) stacking and “wizard hat” parabolic for rhombohedral (ABCA) stacking.
Investigation of length-dependent characteristics of the voltage-induced metal insulator transition in VO2 film devices
Authors: Yoon Joonseok , Lee Giyong , Park Changwoo , Mun Bongjin Simon , Ju Honglyoul
Published: August 2014

The characteristics of the voltage-induced metal insulator transition (MIT) of VO2 film devices are investigated as a function of ambient temperature and length. At the onset of voltage-induced MIT, an abrupt formation of a conduction channel is observed within the insulating phase. The carrier density of the device varies with ambient temperature (TA) and device length (L) across MIT. As the device length is reduced, a statistically random appearance of the conduction channel is observed. Our results suggest that the primary operation principles of the VO2 device can be chosen between Joule heating effect and the electric field effect.
Enhancing phonon flow through one-dimensional interfaces by impedance matching
Authors: Polanco Carlos A. , Ghosh Avik W.
Published: August 2014

We extend concepts from microwave engineering to thermal interfaces and explore the principles of impedance matching in 1D. The extension is based on the generalization of acoustic impedance to nonlinear dispersions using the contact broadening matrix Γ(ω), extracted from the phonon self energy. For a single junction, we find that for coherent and incoherent phonons, the optimal thermal conductance occurs when the matching Γ(ω) equals the Geometric Mean of the contact broadenings. This criterion favors the transmission of both low and high frequency phonons by requiring that (1) the low frequency acoustic impedance of the junction matches that of the two contacts by minimizing the sum of interfacial resistances and (2) the cut-off frequency is near the minimum of the two contacts, thereby reducing the spillage of the states into the tunneling regime. For an ultimately scaled single atom/spring junction, the matching criterion transforms to the arithmetic mean for mass and the harmonic mean for spring constant. The matching can be further improved using a composite graded junction with an exponential varying broadening that functions like a broadband antireflection coating. There is, however, a trade off as the increased length of the interface brings in additional intrinsic sources of scattering.
A new approach to investigate leakage current mechanisms in infrared photodiodes from illuminated current-voltage characteristics
Authors: Gopal Vishnu
Published: August 2014

This paper presents a new approach to investigate leakage current mechanisms in infrared photodiodes from the illuminated current–voltage characteristics. The example of mid-wave mercury cadmium telluride photodiodes is presented to illustrate the new approach. The new method is suitable for evaluating diodes in an array environment as advance knowledge of any of the material or device parameters are not required. The thermal saturation current is estimated from the observed open circuit voltage and zero-bias current (photo-current) of the diode. The ohmic shunt resistance is estimated from the observed maximum dynamic impedance of the diode. The experimentally observed reverse bias diode current in excess of thermal current, photo-current, and ohmic shunt current is reported to be best described by an exponential function of the type, Iexcess = Ir0 + K1 exp (K2 V), where Ir0, K1, and K2 are fitting parameters and V is the applied bias voltage. Our investigations reveal a close link between the excess current and the sources of ohmic currents in the diode. Exponential growth of excess current with the applied bias voltage has been interpreted as an indication of soft breakdown of the diodes.
Vascular smooth muscle cell culture in microfluidic devices
Authors: Wei Y. C. , Chen F. , Zhang T. , Chen D. Y. , Jia X. , Wang J. B. , Guo W. , Chen J.
Published: August 2014

This paper presents a microfluidic device enabling culture of vascular smooth muscle cells (VSMCs) where extracellular matrix coating, VSMC seeding, culture, and immunostaining are demonstrated in a tubing-free manner. By optimizing droplet volume differences between inlets and outlets of micro channels, VSMCs were evenly seeded into microfluidic devices. Furthermore, the effects of extracellular matrix (e.g., collagen, poly-l-Lysine (PLL), and fibronectin) on VSMC proliferation and phenotype expression were explored. As a platform technology, this microfluidic device may function as a new VSMC culture model enabling VSMC studies.
A study of nonlinear lasing dynamics of an InGaAs/AlGaAs/GaAs heterostructure power laser-thyristor emitting at 905 nm
Authors: Slipchenko S. O. , Podoskin A. A. , Rozhkov A. V. , Pikhtin N. A. , Tarasov I. S. , Bagaev T. A. , Konyaev V. P. , Ladugin M. A. , Marmalyuk A. A. , Padalitsa A. A. , Simakov V. A.
Published: August 2014

The results obtained demonstrate that the lasing dynamics reflects the current dynamics formed as a result of complex nonlinear couplings within the laser-thyristor heterostructure. The observed specific features mainly result from the appearance of new channels for generation of excess carriers in the p-base. These channels enhance the main optical activation channel formed by the photogeneration due to the absorption of the spontaneous emission from the active region of the laser part of the heterostructure. The additional channels of excess carrier generation may have an optical nature in the case of scattered laser light upon appearance of new high-Q modes. For nearly critical blocked voltages, generation of carriers can be initiated by an avalanche multiplication of photogenerated carriers.
Optical spin polarization and Hanle effect in GaAsSb: Temperature dependence
Authors: Qiu Weiyang , Wang Xingjun , Chen Pingping , Li Ning , Lu Wei
Published: August 2014

Continuous-wave optical orientation spectroscopy and the Hanle effect are used to investigate the optical spin polarization and spin dephasing time (gTs) in GaAsSb with a Sb concentration of ∼6% as a function of temperature. Optical and spin polarizations up to ∼21% were achieved at ∼120 K, and the scaled spin lifetime gTs decreased monotonously from ∼1.5 ns at 5 K to ∼20 ps at 200 K. We demonstrate that the spin properties of GaAs could be modified by incorporating a small percentage of Sb into it, as a result of an increase in the spin–orbit interactions.
Type I and type II band alignments in ZnO/MgZnO bilayer films
Authors: Agrawal Arpana , Dar Tanveer Ahmad , Phase D. M. , Sen Pratima
Published: August 2014

We report the change in the type of band alignments due to an increase in the dopant (Mg) concentration in pulsed laser deposited ZnO/MgZnO bilayer film. The band offset measurements were carried out from the core level shifts as well as valence band maxima in the single as well as the bilayer films. The change in the type of band alignment is attributed to the surface enrichment of Mg at the heterojunction.
Super-harmonic self-pulsations from a time-delayed phase-conjugate optical system
Authors: Dal Bosco Andreas Karsaklian , Wolfersberger Delphine , Sciamanna Marc
Published: August 2014

We provide experimental evidence of super-harmonic self-pulsation in a laser diode with a phase-conjugate optical feedback (PCF), i.e., time-periodic nearly sinusoidal oscillating output power at a frequency being multiple of the external-cavity frequency that corresponds to the long-standing predictions of so-called “external-cavity mode” [G. P. Agrawal and J. T. Klaus, Opt. Lett. 16, 1325–1327 (1991)]. High-harmonic self-pulsations have been so far limited to configurations with long time-delay, hence to relatively small frequencies (<1–2 GHz). By contrast, the reported self-pulsating solutions from PCF are stable in a larger range of feedback strength and with higher-order harmonic number when decreasing the external-cavity time-delay.
Fabrication and characterization of sub-100/10 nm planar nanofluidic channels by triple thermal oxidation and silicon-glass anodic bonding
Authors: Ouyang Wei , Wang Wei
Published: August 2014

We reported the fabrication and characterization of nanofluidic channels by Triple Thermal Oxidation and Silicon-Glass Anodic Bonding. Planar nanochannels with depths from sub-100 nm down to sub-10 nm were realized by this method. A theoretical model was developed to precisely predict the depth of nanochannels. The depth and uniformity of nanochannels showed good stability during anodic bonding. This method is promising for various nanofluidic studies, such as nanofluidic electrokinetics, biomolecule manipulation, and energy conversion.
Bandwidth enhancement in disordered metamaterial absorbers
Authors: Hao Jianping , Lheurette Éric , Burgnies Ludovic , Okada Étienne , Lippens Didier
Published: August 2014

In this letter, we show numerically and experimentally that a positional disorder of a collection of absorbing electromagnetic wave resonators operating in the long wavelength regime dramatically enhances the absorption bandwidth. The demonstration is performed by using single-size ring-shaped thin metal pieces periodically or randomly positioned onto a back-grounded dielectric layer. For periodic array, an optimum in the periodicity is pointed out with a narrow bandwidth, while the increasing influence of coupling effects for resonators in close vicinity explains a three-fold bandwidth enhancement in the case of positional disorder.
Exploring Corporate Lobbyists' Perceptions of Prospective Coalition Partners in Brussels
Authors: Barron Andrew , Hultén Peter
Published: August 2014

Using original data from a survey conducted in 2012, we apply theoretical insights from the literature on strategic alliances to explore Brussels-based corporate lobbyists' perceptions of prospective political partners. We find these perceptions to be driven primarily by strategic considerations. We also uncover instances where the size and nationality of respondents' firms influence their partner evaluations. Surprisingly, we find little evidence that respondents' assessments of lobbying partners are shaped by EU institutional arrangements. Whilst extant literature suggests information and relationships are important preconditions for successful EU lobbying, we expose the specific circumstances when seeking access to these—and other political resources—that can influence corporate lobbyists' perceptions of their partners. Combined, our findings respond to a concern that scholars of interest coalitions focus on why firms lobby in coalitions whilst overlooking how they select their lobbying partners.
Development and evolution of the gynoecium in Myrteae (Myrtaceae)
Authors: Pimentel Rafael R. , Barreira Natália P. , Spala Diego P. , Cardim Nathane B. , Souza Marcelo C. , Sá-Haiad Bárbara , Machado Silvia R. , Rocha Joecildo F. , Santiago-Fernandes Lygia D. R.
Published: August 2014

Characters of the gynoecium are considered potentially significant for the systematics of Myrtaceae. However, only two such characters – ovule number and placentation – have been addressed from an evolutionary perspective. Colleter presence in flowers is a synapomorphy of Myrtales; however, no morphological and histochemical descriptions of such structures have been done in Myrtaceae. Here we analysed the ontogeny and anatomy of the gynoecium combined with the ontogeny, anatomy, ultrastructure, and histochemistry of the colleters to study the evolution of these characters and map their states in the Myrteae phylogenetic tree. Our findings may help elucidate the evolutionary history of this tribe of fleshy-fruit producers so important towards maintaining ecological balance in the rainforest. Floral anatomy and ontogeny were analysed using light microscopy. Colleter samples were processed using standard methods for light and transmission electron microscopy. The main metabolites in colleters were detected via histochemistry. To map character states the program Mesquite version 2.71 was used. The morphological characters of the South American Myrteae here analysed provided an overview of the evolution of gynoecium – with cauline or carpellate placenta – and of colleters, as well as synapomorphies for the clades Plinia + Myrcia and Eugenia + Pimenta. The presence of two integuments in the ovules associated with sclereids and colleters in the gynoecium and the young fleshy fruit assures the efficient dispersal of their seeds. Our findings regarding gynoecium structural diversity of the tribe Myrteae give a new insight on their morphologically uniform flowers.
Investigation of the Photodegradation of Reactive Blue 19 on P-25 Titanium Dioxide: Effect of Experimental Parameters
Authors: Abu Bakar Faridah , Ruzicka Jan-Yves , Nuramdhani Ida , Williamson Bryce E. , Holzenkaempfer Meike , Golovko Vladimir B.
Published: August 2014

The photocatalytic decolorization and degradation of an anthraquinone-based reactive dye, C.I. Reactive Blue 19, was carried out in laboratory-scale experiments with the systematic variation of several operational parameters, including electron acceptor (hydrogen peroxide) concentration, initial pH, use of buffer solution, aeration, and the specific chemical nature of the buffer solution. Photodegradation was performed under simulated natural light, and conditions were chosen to mimic those found in industry. Mineralization and decolorization were monitored by UV-vis spectroscopy and total organic carbon analysis, and kinetics were modelled using an in-series first-order combination mechanism. Reaction products were examined and monitored by high-resolution mass spectrometry. Under the conditions explored, the reaction rate was found to depend not only on pH and electron acceptor concentration, but also on the specific chemical nature of the buffer used.
Do lignite-derived organic amendments improve early-stage pasture growth and key soil biological and physicochemical properties?
Authors: Little Karen R. , Rose Michael T. , Jackson William R. , Cavagnaro Timothy R. , Patti Antonio F.
Published: August 2014

Commercial products derived from lignite (brown coal), sold mainly as humate preparations, are widely promoted as plant growth stimulants leading to higher crop yields. These products are also claimed to improve key indicators of soil health including soil pH and microbial biomass. In a glasshouse setting, we investigated the effect of six lignite-derived amendments applied at the manufacturer’s recommended rate on the early-stage growth of two pasture species, lucerne (Medicago sativa L.) and ryegrass (Lolium multiflorum Lam.). We used two soil types common to south-eastern Australia, and following an 8-week growing period, assessed soil pH, microbial biomass carbon and mycorrhizal colonisation as key indicators of soil health. We hypothesised that humic acid (HA) and macronutrients derived from the products would positively influence pasture growth and soil health indicators. Although significant growth effects were observed in response to some products, the effects were inconsistent across pasture and soil types. Treatment effects on tissue nutrient accumulation were rare, with the exception of increased potassium in ryegrass in one soil amended with raw brown coal, and decreased nitrogen in lucerne in the same soil amended with a granulated, slow-release humate product. Further, we found no consistent trends in mycorrhizal colonisation or microbial biomass carbon in response to individual treatments. Given the variable responses of the plant species and soil types to the amendments used here, we emphasise the need for further mechanistic studies to help understand how these amendments can be used to greatest effect.
Responses of red-backed voles (Myodes gapperi) to windrows of woody debris along forest–clearcut edges
Authors: Sullivan Thomas P. , Sullivan Druscilla S.
Published: August 2014

Context Southern red-backed voles (Myodes gapperi) disappear from clearcuts within the first year or two after harvest, at least in studies in coniferous and mixed forests of western North America. Post-harvest woody debris arranged in large piles and windrows supports populations of M. gapperi on clearcuts and may extend their persistence there. Aims To test the hypotheses (H) that for M. gapperi, (H1) population parameters of abundance, reproduction, and survival would be higher in windrow–forest than isolated windrow sites, and higher or similar to those in interior old forest sites; (H2) connectivity provided by windrow-forest structures will mitigate potential negative effects of clearcuts and abundance of M. gapperi will remain similar at the abrupt edge between forest and new clearcuts; and (H3) connectivity provided by windrow–forest structures will allow increased movements between both habitats. Methods Study areas were located in three forest ecological zones in southern British Columbia, Canada. Populations of M. gapperi were sampled from 2010 to 2012 in three types of habitats on new clearcuts: isolated windrows of woody debris, windrows attached to uncut old forest, and in uncut old forest. Key results Higher mean values of abundance and number of juvenile recruits of M. gapperi in the isolated windrow and windrow–forest sites than forest sites was contrary to our prediction for H1. In support of H2, we could not detect any differences in the mean number of captures among forest, edge and windrow sections of the windrow–forest sites, nor in the mean range length among the three habitat types. For H3, connectivity provided by windrow–forest structures may mitigate potential negative effects on abundance for M. gapperi at the abrupt edge between forest and new clearcuts. Conclusions and Implications Voles did not commonly move between the forest and windrow habitats, but did move readily within forest and within windrows. Substantial movement by M. gapperi within windrows suggested that this microtine will move along windrows and potentially use these paths of connectivity to cross clearcuts. If the prey base is present, windrow connectivity may enhance these open areas for small mustelids and other carnivores and help maintain abundance and diversity of some forest mammals on clearcuts.
Highway proximity and black carbon from cookstoves as a risk factor for higher blood pressure in rural China
Authors: Baumgartner Jill , Zhang Yuanxun , Schauer James J. , Huang Wei , Wang Yuqin , Ezzati Majid
Published: August 2014

Significance

Air pollution is a leading health risk factor and important contributor to regional climate change in China and other parts of Asia. China’s particulate matter (PM) air pollution dramatically exceeds health guidelines and is impacted by industrial emissions, motor vehicles, and household use of biomass and coal fuels. Black carbon (BC) from biomass and fossil fuel burning is a major climate-forcing component of PM. We found that BC exposure from biomass smoke is more strongly associated with blood pressure than total PM mass, and that coexposure to motor vehicle emissions may strengthen BC’s impact. Air pollution mitigation efforts focusing on reducing combustion pollution are likely to have major benefits for climate and human health.
The transition between the niche and neutral regimes in ecology
Authors: Fisher Charles K. , Mehta Pankaj
Published: August 2014

Significance

In recent years, there has been a vigorous debate among ecologists over the merits of two contrasting models of biodiversity: the niche and neutral theories of ecology. Using two different theoretical models of ecological dynamics, we show that there is a transition between a selection-dominated regime (the niche phase) and a drift-dominated regime (the neutral phase). This is analogous to the phase diagram of water, which can be in the solid, liquid, or gas phase, depending on the temperature and pressure. Our results demonstrate how the niche and neutral theories both emerge from the same underlying ecological principles.
Src promotes GTPase activity of Ras via tyrosine 32 phosphorylation
Authors: Bunda Severa , Heir Pardeep , Srikumar Tharan , Cook Jonathan D. , Burrell Kelly , Kano Yoshihito , Lee Jeffrey E. , Zadeh Gelareh , Raught Brian , Ohh Michael
Published: August 2014

Significance

Despite the well-established connection between Ras and Src, there currently is no evidence of direct interaction between these two proteins. We show here that Src binds to and phosphorylates GTP-loaded Ras on a conserved Y32 residue within the switch I region. It has been shown that Raf binds to Ras with an affinity 1,000-fold greater than that of GAP. However, it has remained unclear how GAP is able to outcompete Raf for Ras upon Raf displacement. We show here that Y32 phosphorylation inhibits Raf binding to Ras and concomitantly promotes GAP association and GTP hydrolysis, thereby ensuring unidirectionality to the Ras GTPase cycle. These findings reveal new fundamental mechanistic insight into how Src negatively regulates Ras.
The Cap1–claudin-4 regulatory pathway is important for renal chloride reabsorption and blood pressure regulation
Authors: Gong Yongfeng , Yu Miao , Yang Jing , Gonzales Ernie , Perez Ronaldo , Hou Mingli , Tripathi Piyush , Hering-Smith Kathleen S. , Hamm L. Lee , Hou Jianghui
Published: August 2014

Significance

How the kidney handles chloride reabsorption has long been a mystery. Here, we have discovered a pathway in the kidney that utilizes channel-activating protease 1 and claudin-4 to physiologically regulate tight junction permeability to chloride. Such a pathway not only is important in renal regulation of chloride but also may play key roles in chloride transport across many other epithelia such as the lung, the salivary gland, and the skin. This discovery also attests to a concept of “druggable” tight junction. Proteases or protease-dependent mechanisms may be developed as pharmacological tools to transiently regulate tight junction permeability in the kidney, the intestine, and the blood–brain barrier.
Inhibition of Borna disease virus replication by an endogenous bornavirus-like element in the ground squirrel genome
Authors: Fujino Kan , Horie Masayuki , Honda Tomoyuki , Merriman Dana K. , Tomonaga Keizo
Published: August 2014

Significance

Sequences derived from ancient viruses have been shown to make up a substantial part of animal genomes. Bornaviruses, a genus of nonsegmented, negative-sense RNA virus, also have left their DNA copies in the genomes of a number of vertebrate lineages. Recent studies have demonstrated that some endogenous bornavirus-like elements (EBLs) may have acquired functions in their hosts as a result of exaptation. In this study, we show that protein encoded by an EBL in the genome of the thirteen-lined ground squirrel efficiently blocks infection and replication of extant bornavirus. To our knowledge, this is the first report showing that endogenous nonretroviral RNA virus elements may function in antiviral defense, providing a potential role for RNA virus endogenization in host evolution.
A critical reanalysis of the relationship between genomics and well-being
Authors: Brown Nicholas J. L. , MacDonald Douglas A. , Samanta Manoj Pratim , Friedman Harris L. , Coyne James C.
Published: August 2014

Significance

This article critically reanalyzes the work of Fredrickson et al. [Fredrickson BL, et al. (2013)Proc Natl Acad Sci USA110(33):13684–13689], which claimed to show that distinct dimensions of psychological well-being are differentially correlated with levels of expression of a selection of genes associated with distinct forms of immune response. We show that not only is Fredrickson et al.’s article conceptually deficient, but more crucially, that their statistical analyses are fatally flawed, to the point that their claimed results are in fact essentially meaningless. We believe that our findings may have implications for the reevaluation of other published genomics research based on comparable statistical analyses and that a variant of our methodology might be useful for such a reevaluation.
Transcription factor PREP1 induces EMT and metastasis by controlling the TGF-β–SMAD3 pathway in non-small cell lung adenocarcinoma
Authors: Risolino Maurizio , Mandia Nadia , Iavarone Francescopaolo , Dardaei Leila , Longobardi Elena , Fernandez Serena , Talotta Francesco , Bianchi Fabrizio , Pisati Federica , Spaggiari Lorenzo , Harter Patrick N. , Mittelbronn Michel , Schulte Dorothea , Incoronato Mariarosaria , Di Fiore Pier Paolo , Blasi Francesco , Verde Pasquale
Published: August 2014

Significance

Epithelial–mesenchymal transition (EMT) is a transdifferentiation program implicated in tumor cell dissemination, controlled by networks of transcription complexes responsive to paracrine factors, such as TGF-β. Pre–B-cell leukemia homeobox (Pbx)-regulating protein-1 (PREP1) is a ubiquitous homeodomain transcription factor involved in early development, genomic stability, insulin sensitivity, and hematopoiesis. PREP1 is a haploinsufficient oncosuppressor in mouse tumorigenesis. By characterizing PREP1 as a novel regulator of EMT in human lung adenocarcinoma, we show that PREP1 also harbors prometastatic properties. While autosustaining its activity by stabilizing its transcriptional partner PBX1, PREP1 modulates the responsiveness of lung cancer cells to TGF-β by controlling the expression of two proinvasive transcription factors (SMAD3 and Fos-related antigen 1) implicated in metastasis mechanisms. Thus, PREP1 represents a novel, promising therapeutic target in non-small cell lung cancer.
Ultrafast tissue staining with chemical tags
Authors: Kohl Johannes , Ng Julian , Cachero Sebastian , Ciabatti Ernesto , Dolan Michael-John , Sutcliffe Ben , Tozer Adam , Ruehle Sabine , Krueger Daniel , Frechter Shahar , Branco Tiago , Tripodi Marco , Jefferis Gregory S. X. E.
Published: August 2014

Significance

Cellular and subcellular structures in thick biological samples typically are visualized either by genetically encoded fluorescent proteins or by antibody staining against proteins of interest. However, both approaches have drawbacks. Fluorescent proteins do not survive treatments for tissue preservation well, are available in only a few colors, and often emit weak signals. Antibody stainings are slow, do not penetrate thick samples well, and often result in considerable background staining. We have overcome these limitations by using genetically encoded chemical tags that result in rapid, even staining of thick biological samples with high-signal and low-background labeling. We introduce tools for flies and mice that drastically improve the speed and specificity for labeling genetically marked cells in biological tissues.
Attenuation of human respiratory syncytial virus by genome-scale codon-pair deoptimization
Authors: Le Nouën Cyril , Brock Linda G. , Luongo Cindy , McCarty Thomas , Yang Lijuan , Mehedi Masfique , Wimmer Eckard , Mueller Steffen , Collins Peter L. , Buchholz Ursula J. , DiNapoli Joshua M.
Published: August 2014

Significance

Human respiratory syncytial virus (RSV) is the most important viral agent of serious pediatric respiratory-tract disease. We designed new live attenuated RSV vaccine candidates by codon-pair deoptimization (CPD). Specifically, viral ORFs were recoded to increase the usage of underrepresented codon pairs, leaving amino acid coding unchanged. CPD viruses were temperature-sensitive and grew less efficiently in vitro than wild-type RSV. In addition, the CPD viruses exhibited a range of restriction in mice and African green monkeys that compared favorably with existing attenuated strains presently in clinical studies. This study produced examples of a new type of vaccine candidate for RSV and showed that CPD of a nonsegmented negative-strand RNA virus can rapidly generate vaccine candidates with a range of attenuation.
Ghrelin promotes hepatic lipogenesis by activation of mTOR-PPARγ signaling pathway
Authors: Li Ziru , Xu Geyang , Qin Yan , Zhang Chao , Tang Hong , Yin Yue , Xiang Xinxin , Li Yin , Zhao Jing , Mulholland Michael , Zhang Weizhen
Published: August 2014

Significance

The peripheral effect of ghrelin on energy metabolism has been controversial. Our study demonstrates a direct peripheral effect of ghrelin to increase de novo lipogenesis in hepatocytes. Moreover, we define mammalian target of rapamycin (mTOR)-peroxisome proliferator-activated receptor-γ (PPARγ) signaling pathway as the intracellular target of ghrelin in hepatocytes. The effect of ghrelin is mediated by the direct interaction between raptor and PPARγ. Our study identifies a previously unidentified pathway to treat NFALD via targeting hepatic ghrelin receptor/mTOR/PPARγ.