bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved self‐adaptive genetic algorithm with quantum scheme for electromagnetic optimisation
Authors: Wei Xiao‐Kun , Shao Wei , Zhang Cheng , Li Jia‐Lin , Wang Bing‐Zhong
Published: July 2014

In this study, an accurate and efficient quantum genetic algorithm (QGA) combined with an improved self‐adaptive (SA) scheme is proposed to solve electromagnetic optimisation problems. QGA is employed as the main optimisation frame because of its wider search range and higher efficiency than the conventional genetic algorithm. By introducing an improved SA scheme, the population at each generation is divided into two groups for crossover operation according to the magnitudes of individual fitness values. The crossover probability and mutation rate remain unchanged at the early stage of iterative process while the SA scheme will be carried out for the rest of the iterative process. Moreover, the elitist model is introduced to save the optimal father‐individuals and abandon the worst ones. All these strategies make the whole population nearly converge to the optimal solution very fast. In two numerical examples of filter design and linear array synthesis, the effectiveness of the author's proposed optimisation algorithm, combined with the finite‐difference time‐domain method and finite‐element method in HFSS, respectively, is verified.
Vehicular communication: a survey
Authors: Bhoi Sourav Kumar , Khilar Pabitra Mohan
Published: July 2014

Vehicular communication is an important and emerging area of research in the field of vehicular technology. The development of software and hardware in communication systems leads to the generation of new networks. Many researches and projects have been conducted in this upcoming area. Many government projects have been implemented in the USA, Japan and the European Union. The main objective of using this new technology is to create an accident free environment. New architectures, protocols and implementations of vehicular ad‐hoc network (VANET) have been made in recent years to provide Intelligent Transportation Services. In this study, the authors survey the current issues like development, deployment, security challenges and about the current projects running in different countries. They also survey the mobility models and simulators required to implement VANET. They have also reviewed the emerging applications of VANET which provides services to the end users. At last, they have presented future research problems in VANET. The main motive of this survey is to explore the current ideas in vehicular communication.
Probabilistic power flow of correlated hybrid wind‐photovoltaic power systems
Authors: Aien Morteza , Khajeh Morteza Gholipour , Rashidinejad Masoud , Fotuhi‐Firuzabad Mahmud
Published: July 2014

As a matter of course, the unprecedented ascending penetration of distributed energy resources, mainly harvesting renewable energies such as wind and solar, is concomitant with environmentally friendly concerns. This type of energy resources are innately uncertain and bring about more uncertainties in the power system context, consequently, necessitates probabilistic analysis of the system performance. Moreover, the uncertain parameters may have a considerable level of correlation to each other, in addition to their uncertainties. The two point estimation method (2PEM) is recognised as an appropriate probabilistic method. This study proposes a new methodology for probabilistic power flow studies for such a problem by modifying the 2PEM. The original 2PEM cannot handle correlated uncertain variables, but the proposed method has been equipped with this ability. To justify the impressiveness of the method, two case studies namely the Wood & Woollenberg 6‐bus and the IEEE118‐bus test systems are examined using the proposed method, then the obtained results are compared against the Monte Carlo simulation results. Comparison of the results justifies the effectiveness of the method in the respected area with regards to both accuracy and execution time criteria.
Performance assessment of a low‐cost inertial measurement unit based ultra‐tight global navigation satellite system/inertial navigation system integration for high dynamic applications
Authors: Qin Feng , Zhan Xingqun , Zhan Lei
Published: July 2014

Owing to large Doppler shifts, the signal of global navigation satellite system is difficult to be acquired and tracked by a receiver for high dynamic vehicles, such as missiles, aircrafts and spacecrafts. Hence, the inertial navigation system is usually used to aid the acquisition and tracking. Compared with the traditional scale tracking, the vector tracking has better performances in the navigation robustness and the immunity to interferences. Although the vector tracking aided by a low‐cost inertial measurement unit (IMU) is not as good as the one aided by high‐grade IMU in the tracking performance and stability, the low‐cost IMU based vector tracking loop has lower price, smaller size and lighter weight. Hence, it is valuable to reduce the expense of ultra‐tight integration system. In this paper, an ultra‐tight integration system using the low‐cost IMU based vector tracking is proposed to achieve the vector tracking and navigation for high dynamic applications. As the critical factor in the ultra‐tight integration, the Doppler frequency shift is estimated and compensated to achieve the acquisition and tracking of every satellite. Then, a vector tracking Kalman filter is designed to implement the vector tracking and integrated navigation. To verify the effectiveness of the ultra‐tight integration, an experiment system is built and a high dynamic scenario is simulated. The results prove that the designed ultra‐tight integration system has perfect tracking and navigation performances for high dynamic applications.
Photocurrent spectrum study of a quantum dot single-photon detector based on resonant tunneling effect with near-infrared response
Authors: Weng Q. C. , An Z. H. , Xiong D. Y. , Zhang B. , Chen P. P. , Li T. X. , Zhu Z. Q. , Lu W.
Published: July 2014

We present the photocurrent spectrum study of a quantum dot (QD) single-photon detector using a reset technique which eliminates the QD's “memory effect.” By applying a proper reset frequency and keeping the detector in linear-response region, the detector's responses to different monochromatic light are resolved which reflects different detection efficiencies. We find the reset photocurrent tails up to 1.3 μm wavelength and near-infrared (∼1100 nm) single-photon sensitivity is demonstrated due to interband transition of electrons in QDs, indicating the device a promising candidate both in quantum information applications and highly sensitive imaging applications operating in relative high temperatures (>80 K).
Breakdown assisted by a novel electron drift injection in the J-TEXT tokamak
Authors: Wang Nengchao , Jin Hai , Zhuang Ge , Ding Yonghua , Pan Yuan , Cen Yishun , Chen Zhipeng , Huang Hai , Liu Dequan , Rao Bo , Zhang Ming , Zou Bichen
Published: July 2014

A novel electron drift injection (EDI) system aiming to improve breakdown behavior has been designed and constructed on the Joint Texas EXperiment Tokamak Tokamak. Electrons emitted by the system undergo the E×B drift, ∇B drift and curvature drift in sequence in order to traverse the confining magnetic field. A local electrostatic well, generated by a concave-shaped plate biased more negative than the cathode, is introduced to interrupt the emitted electrons moving along the magnetic field line (in the parallel direction) in an attempt to bring an enhancement of the injection efficiency and depth. A series of experiments have demonstrated the feasibility of this method, and a penetration distance deeper than 9.5 cm is achieved. Notable breakdown improvements, including the reduction of breakdown delay and average loop voltage, are observed for discharges assisted by EDI. The lower limit of successfully ionized pressure is expanded.
Lie-transform theory of transport in plasma turbulence
Authors: Wang Shaojie
Published: July 2014

From the Vlasov equation, a phase-space transport equation is derived by using the Lie-transform approach, and its connection with the quasilinear transport, nonlinear stochastic transport, and fractional transport equations are discussed. The phase-space transport equation indicates a particle redistribution in the real space induced by the inhomogeneity in the energy space distribution and by the correlation between the change of position and the change of energy.
Double-hybrid density-functional theory applied to molecular crystals
Authors: Sharkas Kamal , Toulouse Julien , Maschio Lorenzo , Civalleri Bartolomeo
Published: July 2014

We test the performance of a number of two- and one-parameter double-hybrid approximations, combining semilocal exchange-correlation density functionals with periodic local second-order Møller-Plesset (LMP2) perturbation theory, for calculating lattice energies of a set of molecular crystals: urea, formamide, ammonia, and carbon dioxide. All double-hybrid methods perform better on average than the corresponding Kohn-Sham calculations with the same functionals, but generally not better than standard LMP2. The one-parameter double-hybrid approximations based on the PBEsol density functional give lattice energies per molecule with an accuracy of about 6 kJ/mol, which is similar to the accuracy of LMP2. This conclusion is further verified on molecular dimers and on the hydrogen cyanide crystal.
An efficient gigawatt level X-band Cerenkov type oscillator without guiding magnetic field
Authors: Guo Liming , Shu Ting , Li Zhiqiang , Zhang Hua , Ju Jinchuan
Published: July 2014

This paper presents a novel modification of gigawatt level X-band Cerenkov type high power microwave oscillator without guiding magnetic field. A confining cathode is put forward to suppress the radial dispersion of the annular relativistic electron beam and accordingly improve its axial transportation to ensure further beam-wave interaction. An overmoded nonuniform slow wave structure is adopted in order to increase the power capacity of the oscillator and the efficiency of beam-wave interaction. A tapered collector is used to collect the beam, increase the Q-factor, and extract the microwave favorably. The simulation results indicate that a microwave is generated by the proposed oscillator with output power of 1.9 GW and frequency of 9.02 GHz, when the diode voltage and beam current are 620 kV and 9 kA, respectively. The corresponding power conversion efficiency is 34%.
Formation of current sheets in magnetic reconnection
Authors: Boozer Allen H.
Published: July 2014

An ideal evolution of magnetic fields in three spatial dimensions tends to cause neighboring field lines to increase their separation exponentially with distance ℓ along the lines, δ(ℓ)=δ(0)eσ(ℓ). The non-ideal effects required to break magnetic field line connections scale as e−σ, so the breaking of connections is inevitable for σ sufficiently large—even though the current density need nowhere be large. When the changes in field line connections occur rapidly compared to an Alfvén transit time, the constancy of j||/B along the magnetic field required for a force-free equilibrium is broken in the region where the change occurs, and an Alfvénic relaxation of j||/B occurs. Independent of the original spatial distribution of j||/B, the evolution is into a sheet current, which is stretched by a factor eσ in width and contracted by a factor eσ in thickness with the current density j|| increasing as eσ. The dissipation of these sheet currents and their associated vorticity sheets appears to be the mechanism for transferring energy from a reconnecting magnetic field to a plasma. Harris sheets, which are used in models of magnetic reconnection, are shown to break up in the direction of current flow when they have a finite width and are in a plasma in force equilibrium. The dependence of the longterm nature of magnetic reconnection in systems driven by footpoint motion can be studied in a model that allows qualitative variation in the nature of that motion: slow or fast motion compared to the Alfvén transit time and the neighboring footpoints either exponentially separating in time or not.
New iridium complex as additive to the spiro-OMeTAD in perovskite solar cells with enhanced stability
Authors: Badia Laura , Mas-Marzá Elena , Sánchez Rafael S. , Barea Eva M. , Bisquert Juan , Mora-Seró Iván
Published: July 2014

A new iridium complex, IrCp*Cl(PyPyz)[TFSI], has been synthesized and used as additive for the hole transporter material, spiro-OMeTAD, in perovskite solar cells. The cells prepared with this Ir additive present higher efficiency than reference cells, and similar to cells prepared with Co additive. We have determined that the presence of metal complexes as additives decreases the recombination rate, as it has been observed by impedance spectroscopy. Very interestingly, while the efficiency after 3 months decreases by 22% and 70% for reference cell and cell with Co additive, respectively, the efficiency of devices containing the Ir additive is only decreased by a 4%.
Graphics processing unit-assisted density profile calculations in the KSTAR reflectometer
Authors: Seo Seong-Heon , Oh Dong Keun
Published: July 2014

Wavelet transform (WT) is widely used in signal processing. The frequency modulation reflectometer in the KSTAR applies this technique to get the phase information from the mixer output measurements. Since WT is a time consuming process, it is difficult to calculate the density profile in real time. The data analysis time, however, can be significantly reduced by the use of the Graphics Processing Unit (GPU), with its powerful computing capability, in WT. A bottle neck in the KSTAR data processing exists in the data input and output (IO) process between the CPU and its peripheral devices. In this paper, the details of the WT implementation assisted by a GPU in the KSTAR reflectometer are presented and the consequent performance improvement is reported. The real time density profile calculation from the reflectometer measurements is also discussed.
Intermediate band conduction in femtosecond-laser hyperdoped silicon
Authors: Sher Meng-Ju , Mazur Eric
Published: July 2014

We use femtosecond-laser hyperdoping to introduce non-equilibrium concentrations of sulfur into silicon and study the nature of the resulting intermediate band. With increasing dopant concentration, the sub-bandgap absorption increases. To better understand the dopant energetics, we perform temperature-dependent Hall and resistivity measurements. We analyze the carrier concentration and the energetics of the intermediate band using a two-band model. The temperature-dependence of the carrier concentration and resistivity suggests that the dopant concentration is below the insulator-to-metal transition and that the samples have a localized intermediate band at 70 meV below the conduction band edge.
Terahertz conductivity and ultrafast dynamics of photoinduced charge carriers in intrinsic 3C and 6H silicon carbide
Authors: Rubano Andrea , Wolf Martin , Kampfrath Tobias
Published: July 2014

The terahertz (THz) conductivity of photoinduced charge carriers in two common polytypes of silicon carbide, 3C-SiC and 6H-SiC, is studied on picosecond time scales using an optical-pump THz-probe technique. We find that the conductivity, measured from 0.7 to 3 THz, is well described by the Drude model, and obtain a velocity relaxation time of 75 fs, independent of sample and charge-carrier density. In contrast, the carrier relaxation rates in the two polytypes differ by orders of magnitude: in 6H- and 3C-SiC, recombination proceeds on a time scale of few picoseconds and beyond nanoseconds, respectively.
Communication: Embedded fragment stochastic density functional theory
Authors: Neuhauser Daniel , Baer Roi , Rabani Eran
Published: July 2014

We develop a method in which the electronic densities of small fragments determined by Kohn-Sham density functional theory (DFT) are embedded using stochastic DFT to form the exact density of the full system. The new method preserves the scaling and the simplicity of the stochastic DFT but cures the slow convergence that occurs when weakly coupled subsystems are treated. It overcomes the spurious charge fluctuations that impair the applications of the original stochastic DFT approach. We demonstrate the new approach on a fullerene dimer and on clusters of water molecules and show that the density of states and the total energy can be accurately described with a relatively small number of stochastic orbitals.
Interacting pairs in natural orbital functional theory
Authors: Piris M.
Published: July 2014

An interacting-pair model is considered to attain a new natural orbital functional (NOF). The new approach, which will be termed PNOF6, belongs to the $\mathcal {JKL}$JKL-only family of NOFs known in the literature as PNOFi. Accordingly, the approximated two-particle reduced density matrix (RDM) is reconstructed from the one-particle RDM, considering an explicit form of the two-particle cumulant in terms of the occupation numbers, and enforcing (2,2)-positivity conditions for the N-representability of the 2-RDM. PNOF6 is superior to its predecessor, PNOF5, which is an independent-pair approach. The functional is able to treat both dynamic and static correlations, thereby putting together the advantages of the other members of this series. The theory is applied to the dissociation of selected diatomic molecules. The equilibrium distances, dipole moments, harmonic frequencies, anharmonicity constants, and binding energies of the considered molecules are presented. Comparative potential energy curves for the deformation of benzene are given at the PNOF5 and PNOF6 levels of theory. In benzene, PNOF5 breaks the symmetry by about 1.5°, with an energy lowering of almost 3 kcal/mol, whereas PNOF6 provides the correct D6h symmetry.
Linear and nonlinear dust acoustic waves in an inhomogeneous magnetized dusty plasma with nonextensive electrons
Authors: El-Taibany W. F. , Selim M. M. , El-Bedwehy N. A. , Al-Abbasy O. M.
Published: July 2014

The propagation of both linear and nonlinear dust acoustic waves (DAWs) in an inhomogeneous magnetized collisional and warm dusty plasma (DP) consisting of Boltzmann ions, nonextensive electrons, and inertial dust particles is investigated. The number density gradients of all DP components besides the inhomogeneities of electrostatic potential and the initial dust fluid velocity are taken into account. The linear dispersion relation and a nonlinear modified Zakharov-Kusnetsov (MZK) equation governing the propagation of the three-dimensional DAWs are derived. The analytical solution of the MZK reveals the creation of both compressive and rarefactive DAW solitons in the proposed model. It is found that the inhomogeneity dimension parameter and the electron nonextensive parameter affect significantly the nonlinear DAW's amplitude, width, and Mach number. The relations of our findings with some astrophysical situations have been given.
Structure transitions induced by the Hall term in homogeneous and isotropic magnetohydrodynamic turbulence
Authors: Miura H. , Araki K.
Published: July 2014

Hall effects on local structures in homogeneous, isotropic, and incompressible magnetohydrodynamic turbulence are studied numerically. The transition of vortices from sheet-like to tubular structures induced by the Hall term is found, while the kinetic energy spectrum does not distinguish the two types of structures. It is shown by the use of the sharp low-pass filter that the transition occurs not only in the scales smaller than the ion skin depth but also in a larger scale. The transition is related with the forward energy transfer in the spectral space. Analyses by the use of the sharp low-pass filter show that the nonlinear energy transfer associated with the Hall term is dominated by the forward transfer and relatively local in the wave number space. A projection of the simulation data to a Smagorinsky-type sub-grid-scale model shows that the high wave number component of the Hall term may possibly be replaced by the model effectively.
L-H transition dynamics in fluid turbulence simulations with neoclassical force balance
Authors: Chôné L. , Beyer P. , Sarazin Y. , Fuhr G. , Bourdelle C. , Benkadda S.
Published: July 2014

Spontaneous transport barrier generation at the edge of a magnetically confined plasma is reproduced in flux-driven three-dimensional fluid simulations of electrostatic turbulence. Here, the role on the radial electric field of collisional friction between trapped and passing particles is shown to be the key ingredient. Especially, accounting for the self-consistent and precise dependence of the friction term on the actual plasma temperature allows for the triggering of a transport barrier, provided that the input power exceeds some threshold. In addition, the barrier is found to experience quasi-periodic relaxation events, reminiscent of edge localised modes. These results put forward a possible key player, namely, neoclassical physics via radial force balance, for the low- to high-confinement regime transition observed in most of controlled fusion devices.
Ultrasonically assisted deposition of colloidal crystals
Authors: Wollmann Sabine , Patel Raj B. , Wixforth Achim , Krenner Hubert J.
Published: July 2014

Colloidal particles are a versatile physical system which have found uses across a range of applications such as the simulation of crystal kinetics, etch masks for fabrication, and the formation of photonic band-gap structures. Utilization of colloidal particles often requires a means to produce highly ordered, periodic structures. One approach is the use of surface acoustic waves (SAWs) to direct the self-assembly of colloidal particles. Previous demonstrations using standing SAWs were shown to be limited in terms of crystal size and dimensionality. Here, we report a technique to improve the spatial alignment of colloidal particles using traveling SAWs. Through control of the radio frequency power, which drives the SAW, we demonstrate enhanced quality and dimensionality of the crystal growth. We show that this technique can be applied to a range of particle sizes in the μm-regime and may hold potential for particles in the sub-μm-regime.
Spin-dependent transport across Co/LaAlO3/SrTiO3 heterojunctions
Authors: Swartz Adrian G. , Harashima Satoshi , Xie Yanwu , Lu Di , Kim Bongju , Bell Christopher , Hikita Yasuyuki , Hwang Harold Y.
Published: July 2014

The conducting interface formed between LaAlO3 and SrTiO3 exhibits high electron mobility, tunable carrier densities, and is theoretically predicted to have long spin lifetimes. Thus, the LaAlO3/SrTiO3 heterostructure is a promising system for the transportation of spin information. We have investigated spin-dependent transport across Co/LaAlO3/SrTiO3 heterostructures using an all electrical three terminal geometry and observed Lorentzian magnetoresistance typically associated with Hanle spin dephasing. However, such a picture fails to explain all the experimentally observed behavior. Further, experiments with spin-unpolarized Au/LaAlO3/SrTiO3 heterojunctions support an alternative scenario involving current modulation by spin-dependent transport through defect states in the LaAlO3 barrier.
Discriminating chaotic and stochastic dynamics through the permutation spectrum test
Authors: Kulp C. W. , Zunino L.
Published: July 2014

In this paper, we propose a new heuristic symbolic tool for unveiling chaotic and stochastic dynamics: the permutation spectrum test. Several numerical examples allow us to confirm the usefulness of the introduced methodology. Indeed, we show that it is robust in situations in which other techniques fail (intermittent chaos, hyperchaotic dynamics, stochastic linear and nonlinear correlated dynamics, and deterministic non-chaotic noise-driven dynamics). We illustrate the applicability and reliability of this pragmatic method by examining real complex time series from diverse scientific fields. Taking into account that the proposed test has the advantages of being conceptually simple and computationally fast, we think that it can be of practical utility as an alternative test for determinism.
Band alignment of HfO2/In0.18Al0.82N determined by angle-resolved x-ray photoelectron spectroscopy
Authors: Owen Man Hon Samuel , Bhuiyan Maruf Amin , Zhang Zheng , Pan Ji Sheng , Tok Eng Soon , Yeo Yee-Chia
Published: July 2014

The band-alignment of atomic layer deposited (ALD)-HfO2/In0.18Al0.82N was studied by high resolution angle-resolved X-ray photoelectron spectroscopy measurements. The band bending near the HfO2/In0.18Al0.82N interface was investigated, and the potential variation across the interface was taken into account in the band alignment calculation. It is observed that the binding energies for N 1s and Al 2p in In0.18Al0.82N decreases and the corresponding extracted valence band offsets increases with increasing θ (i.e., closer to the HfO2/In0.18Al0.82N interface), as a result of an upward energy band bending towards the HfO2/In0.18Al0.82N interface. The resultant valence band offset and the conduction band offset for the ALD-HfO2/In0.18Al0.82N interface calculated was found to be 0.69 eV and 1.01 eV, respectively.
Intrinsic delay of permeable base transistor
Authors: Chen Wenchao , So Franky , Guo Jing
Published: July 2014

Permeable base transistors (PBTs) fabricated by vacuum deposition or solution process have the advantages of easy fabrication and low power operation and are a promising device structure for flexible electronics. Intrinsic delay of PBT, which characterizes the speed of the transistor, is investigated by solving the three-dimensional Poisson equation and drift-diffusion equation self-consistently using finite element method. Decreasing the emitter thickness lowers the intrinsic delay by improving on-current, and a thinner base is also preferred for low intrinsic delay because of fewer carriers in the base region at off-state. The intrinsic delay exponentially decreases as the emitter contact Schottky barrier height decreases, and it linearly depends on the carrier mobility. With an optimized emitter contact barrier height and device geometry, a sub-nano-second intrinsic delay can be achieved with a carrier mobility of ∼10 cm2/V/s obtainable in solution processed indium gallium zinc oxide, which indicates the potential of solution processed PBTs for GHz operations.
The effects of high temperature processing on the structural and optical properties of oxygenated CdS window layers in CdTe solar cells
Authors: Paudel Naba R. , Grice Corey R. , Xiao Chuanxiao , Yan Yanfa
Published: July 2014

High efficiency CdTe solar cells typically use oxygenated CdS (CdS:O) window layers. We synthesize CdS:O window layers at room temperature (RT) and 270 °C using reactive sputtering. The band gaps of CdS:O layers deposited at RT increase when O2/(O2 + Ar) ratios in the deposition chamber increase. On the other hand, the band gaps of CdS:O layers deposited at 270 °C decrease as the O2/(O2 + Ar) ratios increase. Interestingly, however, our high temperature closed-space sublimation (CSS) processed CdTe solar cells using CdS:O window layers deposited at RT and 270 °C exhibit very similar cell performance, including similar short-circuit current densities. To understand the underlying reasons, CdS:O thin films deposited at RT and 270 °C are annealed at temperatures that simulate the CSS process of CdTe deposition. X-ray diffraction, atomic force microscopy, and UV-visible light absorption spectroscopy characterization of the annealed films reveals that the CdS:O films deposited at RT undergo grain regrowth and/or crystallization and exhibit reduced band gaps after the annealing. Our results suggest that CdS:O thin films deposited at RT and 270 °C should exhibit similar optical properties after the deposition of CdTe layers, explaining the similar cell performance.
Electric field induced oscillating electron mobility in asymmetric wide GaAs/AlxGa1−xAs quantum well structure
Authors: Sahoo Narayan , Sahu Trinath
Published: July 2014

For the first time, we show that an oscillatory enhancement of low temperature electron mobility μ can be achieved in an asymmetric GaAs/AlxGa1−xAs wide quantum well structure by applying an external electric field F perpendicular to the interface plane. We show that the oscillating nature of μ as a function of F is mostly due to the contribution of the higher subband through intersubband effects when there is double subband occupancy. We further show that the wavy nature of μ can be enhanced by increasing the well width, surface electron density, and also by considering a double quantum well structure. Our results can be utilized for low temperature device applications.
Trap-induced photoconductivity in singlet fission pentacene diodes
Authors: Qiao Xianfeng , Zhao Chen , Chen Bingbing , Luan Lin
Published: July 2014

This paper reports a trap-induced photoconductivity in ITO/pentacene/Al diodes by using current-voltage and magneto-conductance measurements. The comparison of photoconductivity between pentacene diodes with and without trap clearly shows that the traps play a critical role in generating photoconductivity. It shows that no observable photoconductivity is detected for trap-free pentacene diodes, while significant photoconductivity is observed in diodes with trap. This is because the initial photogenerated singlet excitons in pentacene can rapidly split into triplet excitons with higher binding energy prior to dissociating into free charge carriers. The generated triplet excitons react with trapped charges to release charge-carriers from traps, leading to a trap-induced photoconductivity in the single-layer pentacene diodes. Our studies elucidated the formation mechanisms of photoconductivity in pentacene diodes with extremely fast singlet fission rate.
Multiwavelength excitation Raman scattering of Cu2ZnSn(SxSe1−x)4 (0 ≤ x ≤ 1) polycrystalline thin films: Vibrational properties of sulfoselenide solid solutions
Authors: Dimitrievska Mirjana , Xie Haibing , Fairbrother Andrew , Fontané Xavier , Gurieva Galina , Saucedo Edgardo , Pérez-Rodríguez Alejandro , Schorr Susan , Izquierdo-Roca Victor
Published: July 2014

In this work, Raman spectroscopy and X-ray diffraction were applied together to evaluate the crystal structure and the phonon modes of photovoltaic grade Cu2ZnSn(SxSe1−x)4 thin films, leading to a complete characterization of their structural and vibrational properties. Vibrational characterization has been based on Raman scattering measurements performed with different excitation wavelengths and polarization configurations. Analysis of the experimental spectra has permitted identification of 19 peaks, which positions are in good accord with theoretical predictions. Besides, the observation of Cu2ZnSnS4-like A symmetry peaks related to S vibrations and Cu2ZnSnSe4-like A symmetry peaks related to Se vibrations, additional Raman peaks, characteristic of the solid solution and previously not reported, are observed, and are attributed to vibrations involving both S and Se anions.
Relationship between CH4 and urinary N outputs in ruminants fed forages: a meta-analysis of the literature
Authors: Sauvant D. , Eugène M. , Giger-Reverdin S. , Archimède H. , Doreau M.
Published: July 2014

Enteric methane (CH4) and faecal and urinary nitrogen (N) are two major pollutants due to ruminants. However, relations between these two components have been seldom studied, and the specific relationships for forage diets are not known. A meta-analysis was conducted using a large database of published data for ruminants fed forages, in which CH4 production, digestibility and urinary N (UN) output were all available. A total of 148 treatments (55 from cattle and 93 from small ruminants) from 29 publications and 56 experiments were used. Globally, there was a positive relationship between CH4 and UN production when expressed either per kg of liveweight or per kg of dry matter (DMI) intake. These relationships were maintained when a subset of 38 experiments that focussed on the influence of variation of DMI were considered. Otherwise, when a subset of 17 experiments that focussed on forage crude protein content were considered, the two equations relating CH4 and UN remained significant but the slopes were much smaller. In conclusion, the positive relationship between CH4 and UN can be mainly explained by the indirect positive influences of DMI or of diet organic matter digestibility on these two parameters.
Separation, detection and characterisation of engineered nanoparticles in natural waters using hydrodynamic chromatography and multi-method detection (light scattering, analytical ultracentrifugation and single particle ICP-MS)
Authors: Proulx Kim , Wilkinson Kevin J.
Published: July 2014

Environmental context
The effects of engineered nanoparticles on the environment and on human health are difficult to evaluate largely because nanoparticles are so difficult to measure. The main problems are that concentrations are low and the engineered nanoparticles are often difficult to distinguish from the environmental matrices in which they are found. We report a separation technique that facilitates the detection of engineered nanoparticles in natural waters.

Abstract
Few analytical techniques are presently able to detect and quantify engineered nanoparticles (ENPs) in the environment. The major challenges result from the complex matrices of environmental samples and the low concentrations at which the ENPs are expected to be found. Separation techniques such as asymmetric flow field flow fractionation (AF4) and more recently, hydrodynamic chromatography (HDC) have been used to partly resolve ENPs from their complex environmental matrices. In this paper, HDC was first coupled to light scattering detectors in order to develop a method that would allow the separation and detection of ENPs spiked into a natural water. Size fractionated samples were characterised using off-line detectors including analytical ultracentrifugation (AUC), dynamic light scattering (DLS) and single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). HDC was able to separate a complex mixture of polystyrene, silver and gold nanoparticles (radii of 60, 40, 20 and 10nm) contained within a river water matrix. Furthermore, the feasibility of using HDC coupled to SP-ICP-MS was demonstrated by detecting 4µgL–1 of a 20-nm (radius) nAg in a river water sample.
Surface expression of the hRSV nucleoprotein impairs immunological synapse formation with T cells
Authors: Céspedes Pablo F. , Bueno Susan M. , Ramírez Bruno A. , Gomez Roberto S. , Riquelme Sebastián A. , Palavecino Christian E. , Mackern-Oberti Juan Pablo , Mora Jorge E. , Depoil David , Sacristán Catarina , Cammer Michael , Creneguy Alison , Nguyen Tuan H. , Riedel Claudia A. , Dustin Michael L. , Kalergis Alexis M.
Published: July 2014

Significance

Human respiratory syncytial virus (hRSV) is the leading cause of bronchiolitis and pneumonia in children worldwide. The induction of poor T-cell immunological memory causes a high susceptibility to reinfections, which contributes to hRSV spread. Previously, we showed that hRSV inhibits T-cell activation by impairing the assembly of the dendritic cell (DC)−T-cell immunological synapse (IS). Here, we show that the nucleoprotein (N) of hRSV—a canonical cytosolic protein—is expressed on the surface of infected DCs. Further, using the supported-lipid-bilayer system (that mimics the DC/ antigen-presenting cells-membrane composition), we observed that the hRSV N interfered with pMHC−T-cell receptor interactions and inhibited IS assembly. We conclude that hRSV N may therefore be instrumental in impairing the host immune response during infection with this virus.
Imatinib in Pulmonary Arterial Hypertension: C‐Kit Inhibition
Authors: Farha Samar , Dweik Raed , Rahaghi Franck , Benza Raymond , Hassoun Paul , Frantz Robert , Torres Fernando , Quinn Deborah A. , Comhair Suzy , Erzurum Serpil , Asosingh Kewal
Published: July 2014

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by severe remodeling of the pulmonary artery resulting in increased pulmonary artery pressure and right ventricular hypertrophy and, ultimately, failure. Bone marrow–derived progenitor cells play a critical role in vascular homeostasis and have been shown to be involved in the pathogenesis of PAH. A proliferation of c‐Kit+ hematopoietic progenitors and mast cells has been noted in the remodeled vessels in PAH. Imatinib, a tyrosine kinase inhibitor that targets c‐Kit, has been shown to be beneficial for patients with PAH. Here we hypothesize that the clinical benefit of imatinib in PAH could be related to c‐Kit inhibition of progenitor cell mobilization and maturation into mast cells. As a corollary to the phase 3 study using imatinib in PAH, blood samples were collected from 12 patients prior to starting study drug (baseline) and while on treatment at weeks 4 and 24. Eight were randomized to imatinib and 4 to placebo. Circulating c‐Kit+ and CD34+ CD133+ hematopoietic progenitors as well as biomarkers of mast cell numbers and activation were measured. Circulating CD34+ CD133+ and c‐Kit+ progenitor cells as well as c‐Kit+/CD34+ CD133+ decreased with imatinib therapy (all P < 0.05). In addition, total tryptase, a marker of mast cell load, dropped with imatinib therapy (P = 0.02) and was related to pulmonary vascular resistance (R = 0.7, P = 0.02). The findings support c‐Kit inhibition as a potential mechanism of action of imatinib in PAH and suggest that tryptase is a potential biomarker of response to therapy.
Geometric Sobolev-like embedding using high-dimensional Menger-like curvature
Authors: Kolasiński Sławomir
Published: July 2014

We study a modified version of Lerman-Whitehouse Menger-like curvature defined for

(
m
+
2
)

(m+2)

points in an

n
n

-dimensional Euclidean space. For

1
≤
l
≤
m
+
2

1 \le l \le m+2

and an 

m
m

-dimensional set

Σ
⊂

R
n

\Sigma \subset R^n

, we also introduce global versions of this discrete curvature by taking the supremum with respect to

(
m
+
2
−
l
)

(m+2-l)

points on 

Σ
\Sigma

. We then define geometric curvature energies by integrating one of the global Menger-like curvatures, raised to a certain power 

p
p

, over all

l
l

-tuples of points on 

Σ
\Sigma

. Next, we prove that if 

Σ
\Sigma

is compact and

m
m

-Ahlfors regular and if

p
p

is greater than the dimension of the set of all

l
l

-tuples of points on 

Σ
\Sigma

(i.e. 

p
>
m
l

p > ml

), then the P. Jones’

β
\beta

-numbers of 

Σ
\Sigma

must decay as 

r

τ

r^{\tau }

with

r
→
0

r \to 0

for some

τ
∈
(
0
,
1
)

\tau \in (0,1)

. If 

Σ
\Sigma

is an immersed

C
1

C^1

manifold or a bilipschitz image of such a set then, it follows that it is Reifenberg flat with vanishing constant; hence (by a theorem of David, Kenig and Toro) an embedded

C

1
,
τ

C^{1,\tau }

manifold. We also define a wide class of other sets for which this assertion is true. After that, we bootstrap the exponent

τ
\tau

to 

α
=
1
−
m
l

/

p

\alpha = 1 - ml/p

, which is optimal due to our theorem with S. Blatt [Adv. Math., 2012]. This gives an analogue of the Morrey-Sobolev embedding theorem
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper W Superscript 2 comma p Baseline left-parenthesis double-struck upper R Superscript m l Baseline right-parenthesis subset-of-or-equal-to upper C Superscript 1 comma alpha Baseline left-parenthesis double-struck upper R Superscript m l Baseline right-parenthesis">

W

2
,
p

(

R

m
l

)
⊆

C

1
,
α

(

R

m
l

)

W^{2,p}(\mathbb {R}^{ml}) \subseteq C^{1,\alpha }(\mathbb {R}^{ml})

but, more importantly, we also obtain a qualitative control over the local graph representations of 

Σ
\Sigma

only in terms of the energy.
KO-rings of full flag varieties
Authors: Zibrowius Marcus
Published: July 2014

We present type-independent computations of the

K
O

\mathrm {KO}

-groups of full flag varieties, i.e. of quotient spaces

G

/

T

G/T

of compact Lie groups by their maximal tori. Our main tool is the identification of the Witt ring, a quotient of the

K
O

\mathrm {KO}

-ring, of these varieties with the Tate cohomology of their complex

K

\mathrm {K}

-ring. The computations show that the Witt ring is an exterior algebra whose generators are determined by representations of

G
G

.
Separate responses of karyopherins to glucose and amino acid availability regulate nucleocytoplasmic transport
Authors: Huang Hsiao-Yun , Hopper Anita K.
Published: July 2014

The importin-β family members (karyopherins) mediate the majority of nucleocytoplasmic transport. Msn5 and Los1, members of the importin-β family, function in tRNA nuclear export. tRNAs move bidirectionally between the nucleus and the cytoplasm. Nuclear tRNA accumulation occurs upon amino acid (aa) or glucose deprivation. To understand the mechanisms regulating tRNA subcellular trafficking, we investigated whether Msn5 and Los1 are regulated in response to nutrient availability. We provide evidence that tRNA subcellular trafficking is regulated by distinct aa-sensitive and glucose-sensitive mechanisms. Subcellular distributions of Msn5 and Los1 are altered upon glucose deprivation but not aa deprivation. Redistribution of tRNA exportins from the nucleus to the cytoplasm likely provides one mechanism for tRNA nuclear distribution upon glucose deprivation. We extended our studies to other members of the importin-β family and found that all tested karyopherins invert their subcellular distributions upon glucose deprivation but not aa deprivation. Glucose availability regulates the subcellular distributions of karyopherins likely due to alteration of the RanGTP gradient since glucose deprivation causes redistribution of Ran. Thus nuclear–cytoplasmic distribution of macromolecules is likely generally altered upon glucose deprivation due to collapse of the RanGTP gradient and redistribution of karyopherins between the nucleus and the cytoplasm.
The ARF tumor suppressor prevents chromosomal instability and ensures mitotic checkpoint fidelity through regulation of Aurora B
Authors: Britigan Eric M.C. , Wan Jun , Zasadil Lauren M. , Ryan Sean D. , Weaver Beth A.
Published: July 2014

The ARF tumor suppressor is part of the CDKN2A locus and is mutated or undetectable in numerous cancers. The best-characterized role for ARF is in stabilizing p53 in response to cellular stress. However, ARF has tumor suppressive functions outside this pathway that have not been fully defined. Primary mouse embryonic fibroblasts (MEFs) lacking the ARF tumor suppressor contain abnormal numbers of chromosomes. However, no role for ARF in cell division has previously been proposed. Here we demonstrate a novel, p53-independent role for ARF in the mitotic checkpoint. Consistent with this, loss of ARF results in aneuploidy in vitro and in vivo. ARF−/−MEFs exhibit mitotic defects including misaligned and lagging chromosomes, multipolar spindles, and increased tetraploidy. ARF−/−cells exhibit overexpression of Mad2, BubR1, and Aurora B, but only overexpression of Aurora B phenocopies mitotic defects observed in ARF−/−MEFs. Restoring Aurora B to near-normal levels rescues mitotic phenotypes in cells lacking ARF. Our results define an unexpected role for ARF in chromosome segregation and mitotic checkpoint function. They further establish maintenance of chromosomal stability as one of the additional tumor-suppressive functions of ARF and offer a molecular explanation for the common up-regulation of Aurora B in human cancers.
A separable domain of the p150 subunit of human chromatin assembly factor-1 promotes protein and chromosome associations with nucleoli
Authors: Smith Corey L. , Matheson Timothy D. , Trombly Daniel J. , Sun Xiaoming , Campeau Eric , Han Xuemei , Yates John R. , Kaufman Paul D.
Published: July 2014

Chromatin assembly factor-1 (CAF-1) is a three-subunit protein complex conserved throughout eukaryotes that deposits histones during DNA synthesis. Here we present a novel role for the human p150 subunit in regulating nucleolar macromolecular interactions. Acute depletion of p150 causes redistribution of multiple nucleolar proteins and reduces nucleolar association with several repetitive element–containing loci. Of note, a point mutation in a SUMO-interacting motif (SIM) within p150 abolishes nucleolar associations, whereas PCNA or HP1 interaction sites within p150 are not required for these interactions. In addition, acute depletion of SUMO-2 or the SUMO E2 ligase Ubc9 reduces α-satellite DNA association with nucleoli. The nucleolar functions of p150 are separable from its interactions with the other subunits of the CAF-1 complex because an N-terminal fragment of p150 (p150N) that cannot interact with other CAF-1 subunits is sufficient for maintaining nucleolar chromosome and protein associations. Therefore these data define novel functions for a separable domain of the p150 protein, regulating protein and DNA interactions at the nucleolus.
Protein Ingestion to Stimulate Myofibrillar Protein Synthesis Requires Greater Relative Protein Intakes in Healthy Older Versus Younger Men
Authors: Moore Daniel R. , Churchward-Venne Tyler A. , Witard Oliver , Breen Leigh , Burd Nicholas A. , Tipton Kevin D. , Phillips Stuart M.
Published: July 2014

Background.

Adequate protein ingestion-mediated stimulation of myofibrillar protein synthesis (MPS) is required to maintain skeletal muscle mass. It is currently unknown what per meal protein intake is required to maximally stimulate the response in older men and whether it differs from that of younger men.

Methods.

We retrospectively analyzed data from our laboratories that measured MPS in healthy older (~71 years) and younger (~22 years) men by primed constant infusion of l-ring-[13C6]phenylalanine after ingestion of varying amounts (0–40 g) of high-quality dietary protein as a single bolus and normalized to body mass and, where available, lean body mass (LBM).

Results.

There was no difference (p = .53) in basal MPS rates between older (0.027±0.04%/h; means ± 95% CI) and young (0.028 ± 0.03%/h) men. Biphase linear regression and breakpoint analysis revealed the slope of first line segment was lower (p < .05) in older men and that MPS reached a plateau after ingestion of 0.40 ± 0.19 and 0.24 ± 0.06 g/kg body mass (p= .055) and 0.60 ± 0.29 and 0.25 ± 0.13 g/kg lean body mass (p < .01) in older and younger men, respectively.

Conclusions.

This is the first report of the relative (to body weight) protein ingested dose response of MPS in younger and older men. Our data suggest that healthy older men are less sensitive to low protein intakes and require a greater relative protein intake, in a single meal, than young men to maximally stimulate postprandial rates of MPS. These results should be considered when developing nutritional solutions to maximize MPS for the maintenance or enhancement of muscle mass with advancing age.