bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic adjustment of queue levels in TCP Vegas‐based networks
Authors: Abolfazli E. , Shah‐Mansouri V.
Published: February 2016

Transmission control protocols (TCPs) are used to control the congestion in the Internet. Various types of TCP protocols have been proposed including TCP Reno, TCP Tahoe and TCP Vegas. Although TCP Reno is widely used for wired communications, TCP Vegas is proved to have better performance in wireless environments. In TCP Reno, to achieve a certain queue level at the intermediate routers, active queue management (AQM) schemes are used. An AQM scheme marks the packets at the intermediate routers and TCP Reno source uses that mark to adjust its speed. However, in TCP Vegas, such scheme is not useable. Consequently, the queue level adjustment is not achievable. A scheme which is employed at the source and adjusts the TCP Vegas parameters dynamically to achieve a certain queue level at the intermediate router is proposed. To the best of the knowledge, this is the first attempt to dynamically adjust the queue levels when TCP Vegas is employed. Our proposed scheme plays the role of AQM in TCP Reno for TCP Vegas. The control scheme presented is designed based on integral backstepping technique and will be applied to the linearised model of TCP Vegas.
Effective filtering solution with low cost small size for common‐mode reduction in dc–dc converters
Authors: Laour M. , Tahmi R.
Published: February 2016

An effective solution is introduced aimed to reduce the size and cost of electromagnetic interference (EMI) filters in dc–dc converters. This method is based on the insertion of small ground inductor (grounded through RF inductor). This technique is suitable for unshielded cables. The RF inductor prevent the return current of the common‐mode (CM) noise at high frequencies, it is inserted between the earth ground (ground reference plane) and the chassis ground of the converter, therefore it isolate the converter chassis from power line ground at high frequencies. As well, maintaining the electrical safety grounding at the power frequency with very low impedance to ground. The efficiency of the proposed method is demonstrated by combining measurements and simulations for the fast testing. The level of CM current is compared versus a specific standard. This allows showing that the EMI emission levels can be reduced by as much as 30 dB.
Reflection mode mm‐wave on‐chip notch filters using coupled hairpin resonators
Authors: Gaskell A.A. , Stander T.
Published: February 2016

An on‐chip implementation of a W‐band filter with dual notches at 82 and 95 GHz is presented. Reflection mode filtering methods are implemented with dual hairpin resonator networks, using the inherent parasitic losses in the resonators to create matched loads at the stopband frequencies of interest while reflecting passband power. Notches of 6 and 10.6 dB stopband insertion loss, and 3.7 and 5.6% relative bandwidths, respectively, were achieved. This represents the first implementation of reflection mode filtering in the W‐band on‐chip.
Design of adder and subtractor circuits in majority logic‐based field‐coupled QCA nanocomputing
Authors: Labrado C. , Thapliyal H.
Published: February 2016

Quantum‐dot cellular automata (QCA) is an emerging field‐coupled nanotechnology that promises to outperform existing CMOS technology. Single‐layer QCA designs of full adder, full subtractor, ripple carry adder, and ripple borrow subtractor is proposed. The proposed designs are improved over both existing single‐layer designs and multilayer designs.
Printed eight‐element MIMO system for compact and thin 5G mobile handest
Authors: Qin Zhongjie , Geyi Wen , Zhang Ming , Wang Jun
Published: February 2016

A new printed MIMO system with eight elements for a 5G mobile terminal is investigated. The MIMO system consists of printed planar inverted‐F antenna elements operating at GSM1900 (1880–1920 MHz), LTE2300 (2300–2400 MHz) and LTE2500 (2540–2620 MHz). The antenna elements have a compact size of 14 mm × 15 mm and are deployed on the non‐metalised part of a PCB with dimensions 136 mm × 68.8 mm × 1 mm. By only utilising radiation pattern diversity, good isolations and envelope correlation coefficients for both MIMO systems are achieved. The mean effective gains of the antenna elements are also presented.
Short waveguide load for millimetre‐wave applications
Authors: Komarov V.V. , Meschanov V.P. , Popova N.F.
Published: February 2016

A compact millimetre‐wave waveguide load with wedge‐shaped dielectric inserts is considered. Its reflectivity is studied numerically and experimentally. Chosen absorber shape and sizes provide good matching over a wide‐frequency range 37.5–53.57 GHz. Simulations are carried out for two options of waveguide sizes.
Achievable secrecy rate of wiretap channels incorporating multi‐input–multi‐output amplify and forward relaying
Authors: Mirzaee Meysam , Akhlaghi Soroush
Published: February 2016

This study discusses the secrecy rate of two‐hop relay‐assisted cooperative wiretap channels, incorporating multi‐antenna amplify and forward relaying in the middle of transmission. In this regard, under the Gaussian code book assumption, three main scenarios including null‐space beamforming (NSBF), rank‐1 beamforming (RBF), and the so‐called general rank beamforming (GRBF) are proposed to be employed at the relay where their achievable secrecy rates are studied. Accordingly, for NSBF, a closed‐form solution is derived, whereas the corresponding optimisation problems are formulated for the remaining cases as a standard semi‐definite programming problem. Though GRBF ranks the first in terms of the achievable secrecy rate, RBF exhibits favourable results with a much lower complexity, as the corresponding optimisation problem runs over a reduced dimension. Moreover, NSBF has a much lower complexity, as it provides an analytical solution at the expense of a decrease in the secrecy rate, and interestingly, it performs quite well when the number of eavesdroppers is less than that of the relay antennas.
Performance analysis of a joint estimator for timing, frequency, and phase with continuous‐phase modulation
Authors: Zhai Wenchao , Li Zan , Si Jiangbo , Bai Jun
Published: February 2016

Performance analysis is presented for the joint estimation of symbol timing, frequency offset, and phase offset with continuous‐phase modulation. In this study, undesirable influences on parameters to be estimated, which arise from the inaccuracy of the already estimated parameters, are computed mathematically. Based on performance analysis, a conditional Cramer‐Rao bound (CRB) is put forward, and a hypothesise is made that phase offset variance with frequency error present should match with the conditional CRB for any digital phase modulation. Moreover, the hypothesis is manifested by analysing the log‐likelihood function in a more general mathematical manner. To alleviate the influences, a data‐aided acquisition and phase‐locked loop tracking algorithm is proposed. The results of Monte Carlo simulations are presented, showing good agreement with theoretical analysis. Simulation results also show that the proposed algorithm can improve performance in terms of phase error variance at the expense of a high signal‐to‐noise ratio threshold.
Improved algorithm for joint detection and decoding on the joint sparse graph for CDMA systems
Authors: Wen Lei , Lei Jing , Su Man
Published: February 2016

Joint sparse graph for code division multiple access systems (JSG‐CDMA) combines multiple accessing (low‐density signature) and forward error correction (low‐density parity check code) techniques, and it achieves satisfactory performance under overloaded conditions. In this study, the authors carry on the research on the joint detection and decoding for JSG‐CDMA, and analyse the syndrome effect of message passing on the JSG by the extrinsic information transfer (EXIT) chart. An improved algorithm for joint detection and decoding on the JSG‐CDMA receiver is proposed, and the convergence behaviour of the algorithm is analysed by EXIT chart. Simulation results show that improved algorithm enhance the system performance significantly with a marginal increase of the computational complexity.
Robust rank‐two beamforming for multicell multigroup multicast
Authors: Liu Binyue , Cheng Yong , Zhou Qiaoqiao
Published: February 2016

In practical cellular communication systems, perfect channel state information is not available at the base stations. Assuming that the channel uncertainty is bounded within a known spherical region, the authors consider in this study robust rank‐two multicast beamforming for multiple groups of users in multicell systems. Worst‐case robust beamforming is designed to guarantee that the predefined signal‐to‐interference‐plus‐noise ratio targets of all users are met for any channel instance in the bounded region. The Alamouti code is employed to double the degrees of freedom in the beamformer design. The authors apply the semi‐definite relaxation (SDR) technique to address the formulated non‐convex robust rank‐two beamforming problem. Analytical results show that the SDR is tight when the number of users in each multicast group is no more than two and the channel uncertainty is sufficiently small. Finally, extensive simulations are carried out to validate the proposed beamforming design and the analytical studies.
Universal soft demodulation schemes for M‐ary phase shift keying and quadrature amplitude modulation
Authors: Zhang Meixiang , Kim Sooyoung
Published: February 2016

In this study, the authors propose an efficient universal soft demodulation method for M‐ary phase shift keying (PSK) and quadrature amplitude modulation (QAM) schemes. The proposed method achieves the same performance as the Max‐log method with much lower, linear‐order complexity. The proposed demodulator recursively maps the detected symbol to a specific region in the first quadrant, so that finally there is only one constellation symbol left in the region, and thus it requires approximately one distance estimation per bit. The authors first derive the equations to estimate soft decision bit information for a few well‐known M‐ary PSK and QAM schemes, and subsequently present compact universal equations applicable to any M‐ary PSK and QAM schemes, respectively. The simulation results reveal that the proposed method produces exactly the same performance as the Max‐log method with greatly reduced computational complexity.
Mode‐dependent event‐triggered control of networked switching Takagi–Sugeno fuzzy systems
Authors: Liu Hao
Published: February 2016

This study presents a novel mode‐dependent event‐triggering (MDET) scheme for networked switching Takagi–Sugeno fuzzy systems. Firstly, a new delay system model for the stability analysis is proposed by considering network‐induced delay. Then, based on this model and mode‐dependent average dwell time method, sufficient conditions are obtained to guarantee the exponential stability. Criteria for co‐designing the event generator parameters and the controller gain matrices are given. Finally, numerical examples are provided to show that the MDET scheme proposed in this study is less conservative than some existing event‐triggering schemes.
Finite‐time stability of interconnected impulsive switched systems
Authors: Zong Guangdeng , Ren Hangli , Hou Linlin
Published: February 2016

In this study, the finite‐time stability problem is addressed concerning interconnected impulsive switched systems. By resorting to the average dwell time approach, a sufficient criterion is provided for interconnected impulsive switched systems to cope with the problem of finite‐time stability. Then, the decentralised switched control scheme based on state‐feedback controller and a class of switching signals are constructed to ensure stabilisability of the system. Finally, an application example is presented to demonstrate the effectiveness of the main results.
Stabilization conditions for fuzzy control of uncertain fractional order non‐linear systems with random disturbances
Authors: Wang Bin , Xue Jianyi , Wu Fengjiao , Zhu Delan
Published: February 2016

A novel fractional order Takagi–Sugeno (T–S) fuzzy control method for a class of fractional order non‐linear systems is proposed in this study. On the basis of the fractional order interval theory, the generalised T–S fuzzy model for a class of uncertain fractional order non‐linear systems is presented. By using fractional order Lyapunov stability theorem, the more relaxed and practical sufficient stability conditions which are presented as a new set of linear matrix inequalities are put forward, which are guaranteed by rigorous mathematical derivation. The proposed control scheme is developed for fractional order non‐linear systems stabilisation in the presence of random disturbances. Typical instances including the fractional order three‐dimensional (3D) non‐linear system and the fractional order 4D non‐linear Lorenz hyperchaos are implemented. Simulation results indicate the designed fractional order T–S fuzzy control scheme works well compared with the existing method.
Adaptive sliding‐mode control for stochastic Markovian jumping systems with actuator faults
Authors: Zhu Jun‐Wei , Yang Guang‐Hong
Published: February 2016

This study is concerned with the fault tolerant control for stochastic Markovian jumping systems with actuator faults including loss of effectiveness, stuck, and outage. By introducing switching laws and according to the information from the adaptive scheme, a novel adaptive sliding mode controller is designed, which ensures the closed‐loop system to be robustly stochastically stable in the presence of actuator faults. Moreover, the reachability of the sliding surface and the stability of the sliding mode dynamics are guaranteed in spite of actuator faults and Markovian jumping. Finally, a simulation example is given to illustrate the effectiveness of the proposed method.
Strategic scheduling of energy storage for load serving entities in locational marginal pricing market
Authors: Fang Xin , Li Fangxing , Wei Yanli , Cui Hantao
Published: February 2016

Cost‐effective approaches of storing electrical energy on a large‐scale can help the grid operate flexibly and reliably. Public utility commissions view energy storage (ES) as a vital yet complementary part of other clean technologies such as renewable generation. As a coherent framework is being mapped out to increase the penetration of renewables in total electricity generation, load serving entities (LSEs) have been encouraged to procure ES systems to hedge against the intermittence and uncertainty of renewable power such as wind. Owing to the increasing penetration of wind generation, it becomes more complex for LSEs to obtain a deterministic ES scheduling decision, i.e. charging/discharging portfolio. To address this challenge, a bi‐level strategic scheduling model is proposed in which the primary objective is to maximise the LSE's profit by optimally scheduling ES charging/discharging profile. The sub‐problem is Independent System Operator's (ISO's) economic dispatch for generation cost minimisation, assuming foreseeable impact in market‐clearing price from ES. This bi‐level model is converted to a stochastic mathematic programme with equilibrium constraints by recasting the lower‐level problem as its Karush–Kuhn–Tucker optimality conditions. Numerical examples based on the PJM 5‐bus and IEEE 118‐ bus systems are presented to demonstrate and validate the proposed approach.
Cross‐gramian‐based dynamic equivalence of wind farms
Authors: Ni Yu , Du Zhengchun , Li Chongtao , Zhang Gang
Published: February 2016

This study presents dynamic equivalence of wind farms using the cross‐gramian (CG)‐based model order reduction method. For the purpose of wind fluctuation simulation, the dynamic model of wind farms can be described as a high‐order linear input–output system, whose input is the wind speed and output is the active power injected from point of common coupling (PCC). The main input–output behaviours of the system can be measured by its CG. The right and left eigenspaces associated with large eigenvalues of CG are used to obtain a low‐order model. Frequency‐domain analysis of wind farms consisted of doubly‐fed induction generators shows that the proposed method is rapid and numerically stable. The non‐linear dynamic simulation also confirms that the reduced model is capable of retaining the dynamic relationship between the input and output of original wind farms. The proposed method offers a potential solution to dynamic simulation of the power system with large‐scale wind farms.
Event‐triggered H∞ Markovian switching pinning control for group consensus of large‐scale systems
Authors: Cui Yanliang , Fei Minrui , Du Dajun
Published: February 2016

This study investigates the pinning control issue for group consensus of large‐scale systems (LSSs) with communication topology changes and network disturbances. A node selection principle is firstly designed to choose appropriate control nodes, and a centralised pinning control protocol is proposed to drive LSSs achieving group consensus. For reducing control command updates, an event‐trigger is employed to determine whether control signal need be changed. Since the node receives compound exogenous disturbances from its communication neighbours, an improved point‐to‐area H∞ index is advocated as a system robustness performance. Considering communication topology changes, an event‐triggered H∞ Markovian switching pinning control law is finally established and a sufficient controller and event‐trigger co‐design method is presented. Under this strategy, the group consensus of LSSs with a pre‐scheduled H∞ performance can be simultaneously achieved while the Markovian switching topologies are tolerated, moreover, only fewer nodes are controlled and seldom control commands are updated. Finally, illustrative examples are given to demonstrate the effectiveness of the proposed theoretical result.
Fault discrimination scheme for power transformer using random forest technique
Authors: Shah Ashesh M. , Bhalja Bhavesh R.
Published: February 2016

This study presents random forest‐based fault discrimination technique for power transformer. The proposed scheme relies on extracting features from the measured data of differential current signals of a power transformer. Various simulation cases consisting of internal faults including special types of turn‐to‐turn and primary‐to‐secondary winding faults and other disturbances (over‐excitation and different types magnetising inrush such as initial, residual, recovery and sympathetic) have been generated with varying fault and system parameters for an existing power transformer of an Indian power transmission network using PSCAD/EMTDC software package. The performance of the proposed scheme has been evaluated over a simulation dataset of 5442 cases and the overall fault discrimination accuracy of more than 98% is achieved. The proposed scheme gives promising results for different connections and various ratings of the transformer, even though it is trained only once for a single rating and connection of a transformer. Comparative evaluation of the proposed scheme with the existing scheme clearly indicates the superiority of the proposed scheme as it remains stable during CT saturation condition and gives better stability during disturbances compared with conventional/existing schemes.
Simple and efficient method for steady‐state voltage stability analysis of islanded microgrids with considering wind turbine generation and frequency deviation
Authors: Hemmatpour Mohammad Hasan , Mohammadian Mohsen , Gharaveisi Ali‐Akbar
Published: February 2016

Distribution grids are being transformed from passive to active networks. The active distribution systems are constructed through the implementation of microgrids (MGs) which are characterised as ‘the building blocks of smart grids’. This type of network eases the integration of distributed generation into power networks and makes it possible to define a new index for voltage stability. The penetration of renewable power sources such as wind turbines can create new challenges in this system that will affect voltage stability index (VSI). In this study, an improved indicator is proposed to estimate the voltage stability margin of a two‐bus system based on both saddle node and limited induced bifurcations considering different types of load model. The catastrophe theory is used to define this new VSI of an islanded MG (IMG), called as cat_VSIIMG. A new concept, named reduced IMG network, is also used to generalise the proposed index to n‐bus IMGs by splitting these networks. The cat_VSIIMG, which is validated by a verified continuation power flow method for IMGs is called the maximum loadability margin of IMG. The performance and effectiveness of the proposed method are demonstrated on 33‐bus and 69‐bus test systems for different types of load model.
Influence of aerosols on the ion‐flow field under high‐voltage direct current transmission lines
Authors: Yi Yong , Zhang Chuyan , Chen Zhengying , Wang Liming
Published: February 2016

In this study, the influence of aerosols on the ion‐flow field has been researched by numerical calculations and experiments. The steady‐state model of ion‐flow field, considering the aerosols, is developed and solved by finite‐element finite‐difference method. The transport model of the particles is introduced by the Lagrangian method and the motion equations are solved by the fourth‐order Runge–Kutta method. In the laboratory, a reduced‐scale line platform is build up to test the influence of the aerosols and used to verify the calculations. From the results of measurements and calculations, it is observed that the calculated results are in good agreement with experimental results.
Spatio‐temporal mean curvature based image sequence restoration
Authors: Ren Fuquan , Qiu Tianshuang
Published: February 2016

In this study, the authors propose a restoration algorithm for blurred and noisy continuous image sequences. The proposed approach treats an image sequence as a space‐time volume and employs a spatio‐temporal mean curvature regularisation which is a novel regularisation proposed in the study to enhance the smoothness of the solution. An augmented Lagrangian method with splitting techniques is used to handle the problem, iteratively finding solutions to the subproblems. Experiments show that the proposed approach can produce higher quality results and more natural images comparing with other space‐time volume based methods on image sequence denoising and deblurring problems.
Integration of colour and uniform interlaced derivative patterns for object tracking
Authors: Fatemeh Razavi Seyedeh , Sajedi Hedieh , Ebrahim Shiri Mohammad
Published: February 2016

Object tracking as a branch of computer vision plays a key role in the intelligent video surveillance. In recent years, the mean shift algorithm due to its simplicity and robustness has attracted great attention for tracking the object by using a colour model, while only using the colour causes the error in some cases of tracking such as illumination variations and so on. Consequently, the authors proposed an enhanced mean shift tracking algorithm. First, they presented a new texture‐based target representation by a modified version of the interlaced derivative pattern, which considers spatial dependencies between pixels. Second, an improvement for the mean shift tracking algorithm based on this representation is suggested. In addition, a parameter to resize the window around the object is considered, adaptively. Experimental results on some benchmark video in comparison with other state‐of‐art methods show the efficiency and utility of the proposed algorithm in many complex conditions.
Electrocardiogram signal compression using singular coefficient truncation and wavelet coefficient coding
Authors: Kumar Ranjeet , Kumar Anil , Singh Girish Kumar
Published: February 2016

In this study, an inter‐ and intra‐beat correlation‐based compression technique for electrocardiogram (ECG) signal is proposed using singular coefficient truncation, based on singular value decomposition (SVD) and adaptive scanning wavelet difference reduction technique. In this method, correlated beat segments are arranged in N × M array, and processed with proposed compression technique. Initially, array is decomposed into triplets using SVD in which most significant energy is concentrated in first few singular values. The insignificant energy coefficients are truncated and array is retained with few significant singular coefficients. Retained array is further processed with ASDWR coding technique to achieve higher compression. The proposed technique is tested on several MIT‐BIH arrhythmia ECG signal records, and performance is evaluated in form of compression ratio (CR), percentage root‐mean square difference (PRD), signal‐to‐noise ratio and cross‐correlation. The evaluation results illustrate that the proposed algorithm has achieved the CR of 24.85:1 with an excellent quality of signal reconstruction in terms of PRD as 1.89% for ECG signal Rec. 100.
Automatic and predictive fractionation of organic micropollutants in contaminated water
Authors: Brogat Marine , Baures Estelle , Sellier Amelie , Mercier Fabien , Doloy Marie , Thomas Olivier , Roig Benoit
Published: February 2016

Environmental context The safeguarding of water supplies and drinking water is a major issue when considering human health risk management. In this context, an automatic and on-site fractionation system for the detection of organic contaminants has been developed. The main goal of this system is to establish an initial diagnosis by identifying a class of substances involved in a case of pollution. Abstract This paper proposes a new approach for the preconcentration, fractionation, prediction and detection of organic micropollutants in water. The main aim of this study was to implement an innovative fractionation method and a prediction model based on the physicochemical properties of compounds and interactions with the sorbent of solid-phase extraction cartridges. Two sorbents (Strata-SAX and Oasis-HLB) and three specific eluting solvents (mixture of methanol and sodium chloride and mixtures of acetonitrile and ultrapure water) were used to separate organic compounds into five specific fractions according to their physicochemical properties (anionic and cationic or neutral compounds with various polarity). More than 75 molecules (43 molecules individually studied and a mixture with 43 molecules, including 11 molecules individually studied) including pesticides, pharmaceuticals, endocrine disruptors and polycyclic aromatic hydrocarbons, with various properties were studied, and the results showed that the elution fraction can be predicted for more than 85% of the compounds. This methodology could simplify the analytical chain by reducing detailed analysis on limited categories of compounds, and could be used for a rapid and on-site screening of organic compounds.
The Serotonin Transporter Promotes a Pathological Estrogen Metabolic Pathway in Pulmonary Hypertension via Cytochrome P450 1B1
Authors: Johansen Anne Katrine Z. , Dean Afshan , Morecroft Ian , Hood Katie , Nilsen Margaret , Loughlin Lynn , Anagnostopoulou Aikaterini , Touyz Rhian M. , White Kevin , MacLean Margaret R.
Published: February 2016

Pulmonary arterial hypertension (PAH) is a devastating vasculopathy that predominates in women and has been associated with dysregulated estrogen and serotonin signaling. Overexpression of the serotonin transporter (SERT+) in mice results in an estrogen‐dependent development of pulmonary hypertension (PH). Estrogen metabolism by cytochrome P450 1B1 (CYP1B1) contributes to the pathogenesis of PAH, and serotonin can increase CYP1B1 expression in human pulmonary arterial smooth muscle cells (hPASMCs). We hypothesized that an increase in intracellular serotonin via increased SERT expression may dysregulate estrogen metabolism via CYP1B1 to facilitate PAH. Consistent with this hypothesis, we found elevated lung CYP1B1 protein expression in female SERT+ mice accompanied by PH, which was attenuated by the CYP1B1 inhibitor 2,3′,4,5′‐tetramethoxystilbene (TMS). Lungs from female SERT+ mice demonstrated an increase in oxidative stress that was marked by the expression of 8‐hydroxyguanosine; however, this was unaffected by CYP1B1 inhibition. SERT expression was increased in monocrotaline‐induced PH in female rats; however, TMS did not reverse PH in monocrotaline‐treated rats but prolonged survival. Stimulation of hPASMCs with the CYP1B1 metabolite 16α‐hydroxyestrone increased cellular proliferation, which was attenuated by an inhibitor (MPP) of estrogen receptor alpha (ERα) and a specific ERα antibody. Thus, increased intracellular serotonin caused by increased SERT expression may contribute to PAH pathobiology by dysregulation of estrogen metabolic pathways via increased CYP1B1 activity. This promotes PASMC proliferation by the formation of pathogenic metabolites of estrogen that mediate their effects via ERα. Our studies indicate that targeting this pathway in PAH may provide a promising antiproliferative therapeutic strategy.
Uncovering homo-and hetero-interactions on the cell membrane using single particle tracking approaches
Authors: Torreno-Pina Juan A , Manzo Carlo , Garcia-Parajo Maria F
Published: February 2016

The plasma membrane of eukaryotic cells is responsible for a myriad of functions that regulate cell physiology and plays a crucial role in a multitude of processes that include adhesion, migration, signaling recognition and cell–cell communication. This is accomplished by specific interactions between different membrane components such as lipids and proteins on the lipid bilayer but also through interactions with the underlying cortical actin cytoskeleton on the intracellular side and the glycocalyx matrix in close proximity to the extracellular side. Advanced biophysical techniques, including single particle tracking (SPT) have revealed that the lateral diffusion of molecular components on the plasma membrane represents a landmark manifestation of such interactions. Indeed, by studying changes in the diffusivity of individual membrane molecules, including sub-diffusion, confined diffusion and/or transient arrest of molecules in membrane compartments, it has been possible to gain insight on the nature of molecular interactions and to infer on its functional role for cell response. In this review, we will revise some exciting results where SPT has been crucial to reveal homo- and hetero-interactions on the cell membrane.
Second harmonic generation and two-photon luminescence from colloidal gold nanoparticles
Authors: Yashunin D A , Korytin A I , Smirnov A I , Stepanov A N
Published: February 2016

Second harmonic generation and two-photon luminescence from colloidal gold nanoparticles in the 980–1300 nm wavelength range of exciting femtosecond radiation were investigated experimentally. The measured polarization and spectral characteristics of the second harmonic and two-photon luminescence demonstrate that the observed nonlinear optical signal is determined by the dimers constituting several percent of the total nanoparticle number.
Fast tomographic measurements of temperature in an air plasma cutting torch
Authors: Hlína J , Šonský J , Gruber J , Cressault Y
Published: February 2016

Temperatures in an air plasma jet were measured using a tomographic experimental arrangement providing time-resolved scans of plasma optical radiation in the spectral band 559–601 nm from two directions. The acquired data and subsequent processing yielded time-resolved temperature distributions in measurement planes perpendicular to the plasma jet axis with a temporal resolution of 1 μs. The measurement system and evaluation methods afforded detailed information about the influence of high-frequency ripple modulation of the arc current on plasma temperature.
Dominant particles and reactions in a two-temperature chemical kinetic model of a decaying SF6 arc
Authors: Wang Xiaohua , Gao Qingqing , Fu Yuwei , Yang Aijun , Rong Mingzhe , Wu Yi , Niu Chunping , Murphy Anthony B
Published: February 2016

This paper is devoted to the computation of the non-equilibrium composition of an SF6 plasma, and determination of the dominant particles and reactions, at conditions relevant to high-voltage circuit breakers after current zero (temperatures from 12 000 K to 1000 K and a pressure of 4 atm). The non-equilibrium composition is characterized by departures from both thermal and chemical equilibrium. In thermal non-equilibrium process, the electron temperature (T
e) is not equal to the heavy-particle temperature (T
h), while for chemical non-equilibrium, a chemical kinetic model is adopted. In order to evaluate the reasonableness and reliability of the non-equilibrium composition, calculation methods for equilibrium composition based on Gibbs free energy minimization and kinetic composition in a one-temperature kinetic model are first considered. Based on the one-temperature kinetic model, a two-temperature kinetic model with the ratio T
e/T
h varying as a function of the logarithm of electron density ratio (n
e/

) was established. In this model, T* is introduced to allow a smooth transition between T
h and T
e and to determine the temperatures for the rate constants. The initial composition in the kinetic models is obtained from the asymptotic composition as infinite time is approached at 12 000 K. The molar fractions of neutral particles and ions in the two-temperature kinetic model are consistent with the equilibrium composition and the composition obtained from the one-temperature kinetic model above 10 000 K, while significant differences appear below 10 000 K. Based on the dependence of the particle distributions on temperature in the two-temperature kinetic model, three temperature ranges, and the dominant particles and reactions in the respective ranges, are determined. The full model is then simplified into three models and the accuracy of the simplified models is assessed. The simplified models reduce the number of species and reactions by a factor of about 2, while providing results that agree closely with the full model. Thus, the physicochemical processes of SF6 arc can be characterized by relatively few species and reactions in each temperature range. It is noted that the simplified models can also be applied to a wide range of pressures, 1–16 atm, conditions which cover most circuit breaker applications. The simplified species and reactions will allow the computing time of multi-dimensional models, taking into account departures from both thermal and chemical equilibrium, to be decreased dramatically while capturing the main physicochemical processes in SF6 arcs.
Enhanced Second Harmonic Generation in AU/AI2O3/AU absorber
Authors: Huang Fenglun , Bai Songang , Li Qiang , Qu Yurui , Min Qiu
Published: February 2016

A kind of metal-insulator-metal (MIM) metamaterial absorber for generating second harmonic signal is investigated. The absorbers exhibit high absorption efficiency at the dip and notably enhance the generated second harmonic signal by a factor of over 30, in contrast to an Au/alumina double-layer without Au disk on the top. This study demonstrates the potential of metamaterial absorber for nonlinear photonics.
The ordering alignment of gold nanorods in liquid crystals and its applications to polarization-sensitive SERS
Authors: Wang Y L , Chen L Y , Liu Q K , Cai F H , Qian J
Published: February 2016

Gold nanorods (GNRs) were synthesized, coated with poly(ethylene glycol) (PEG) chains, and uniformly dispersed into the lyotropic nematic liquid crystal (LC) matrix by our proposed method. The GNRs-LC composites were found to exhibit good stability over days and have high density of GNRs. The extinction spectra of the composites were found to be polarization sensitive when the shearing force were applied, due to the alignment of GNRs driven by the LC molecules, which was also in accordance to the simulation results. A type of Raman reporter, 3,3'-diethylthiatricarbocyanine iodide (DTTC), was co-conjugated onto the GNRs with PEG molecules, and then incorporated into the LC matrix. Thus, its Raman signals could be enhanced by the localized surface plasmon resonance (LSPR) of the GNRs. These surface-enhanced Raman scattering (SERS) signals were found to be polarization sensitive when the shearing force was applied, due to the polarization sensitive enhancement of the local field of GNRs. The nanocomposites with tunable SPR peaks and SERS signals have potential applications in optoelectronic devices.
Study of humidity on the structure and optical properties of cesium iodide thin film
Authors: Liang Bo , Liu Shuang , Guo Lina , Chen Dejun , Liu Yong , Zhong Zhiyong , Xiong Liufeng
Published: February 2016

We report the influence of 70% 5% humid exposed air at room temperature on the structure of 500nm thick CsI film. By means of scanning electron microscopy (SEM) and X- ray diffusion (XRD) analysis, the surface morphology and polycrystalline structure were investigated. After 24 hour exposure to humid air, the grain size of CsI film has a drastic change, and so as to the preferential growth orientation. Infrared spectra showed a hydroxyl absorption peak after 3h exposure. And in long term exposure (24h), the absorption peak broadened with the band center shifting toward lower wavenumbers.
Direct phase extraction of self-mixing displacement measurement using Hilbert transform
Authors: Tao Yufeng , Wang Ming , Guo Dongmei , Zhang Jiahuan
Published: February 2016

Signals of a self-mixing interferometer established on a semiconductor laser diode are analyzed. Phase is extracted out for decoding measurement which contained in self-mixing fringes. The semiconductor laser diode works as light source and receiver without modulation. By combining Hilbert transform with phase condition of self-mixing interference, micron- displacement is reconstructed by phase information at week or even moderate feedback level. Theoretical analysis and simulation results are presented before verification of experimental measurement. Practical feedback level is estimated by a data fitting technique with a programmable high-resolution PZT. Consistence of the results promises that direct phase extraction on self-mixing interferometer is available for micron-displacement measurement with a nanometer accuracy.
An efficient model to predict guided wave radiation by finite-sized sources in multilayered anisotropic plates with account of caustics
Authors: Stévenin M , Lhémery A , Grondel S
Published: February 2016

Elastic guided waves (GW) are used in various non-destructive testing (NDT) methods to inspect plate-like structures, generated by finite-sized transducers. Thanks to GW long range propagation, using a few transducers at permanent positions can provide a full coverage of the plate. Transducer diffraction effects take place, leading to complex radiated fields. Optimizing transducers positioning makes it necessary to accurately predict the GW field radiated by a transducer. Fraunhofer-like approximations applied to GW in isotropic homogeneous plates lead to fast and accurate field computation but can fail when applied to multi-layered anisotropic composite plates, as shown by some examples given.

Here, a model is proposed for composite plates, based on the computation of the approximate Green's tensor describing modal propagation from a source point, with account of caustics typically seen when strong anisotropy is concerned. Modal solutions are otherwise obtained by the Semi-Analytic Finite Element method. Transducer diffraction effects are accounted for by means of an angular integration over the transducer surface as seen from the calculation point, that is, over energy paths involved, which are mode-dependent. The model is validated by comparing its predictions with those computed by means of a full convolution integration of the Green's tensor with the source over transducer surface. Examples given concern disk and rectangular shaped transducers commonly used in NDT.
Large proper motion of the Thorne–Żytkow object candidate HV 2112 reveals its likely nature as foreground Galactic S-star
Authors: Maccarone Thomas J. , de Mink Selma E.
Published: February 2016

Using the Southern Proper Motion (SPM) catalogue, we show that the candidate Thorne–Żytkow object HV 2112 has a proper motion implying a space velocity of about 3000$\,\rm {km}\,\rm {s}^{-1}$if the object is located at the distance of the Small Magellanic Cloud (SMC). The proper motion is statistically different from that of the SMC at approximately 4σ in SPM, although the result can drop to about 3σ significance by including the UCAC4 data and considering systematic uncertainties in addition to the statistical ones. Assuming the measurement is robust, this proper motion is sufficient to exclude its proposed membership of the SMC and to argue instead that it is likely to be a foreground star in the Milky Way halo. The smaller distance and therefore lower brightness argue against its proposed nature as a Thorne–Żytkow object (the hypothesized star-like object formed when a normal star and a neutron star merge) or a Asymptotic Giant Branch (AGB) star. Instead we propose a binary scenario where this star is the companion of a former massive AGB star, which polluted the object with via its stellar wind, i.e. a special case of an extrinsic S star. Our new scenario solves two additional problems with the two existing scenarios for its nature as Thorne–Żytkow object or present-day super AGB star. The puzzling high ratio of the strength of calcium to iron absorption lines is unexpected for SMC supergiants, but is fully consistent with the expectations for halo abundances. Secondly, its strong variability can now be explained naturally as a manifestation of the Mira phenomenon. We discuss further observational tests that could distinguish between the foreground and SMC scenarios in advance of the improved proper motion measurements likely to come from Gaia.
The Lyman-continuum photon production efficiency in the high-redshift Universe
Authors: Wilkins Stephen M. , Feng Yu , Di-Matteo Tiziana , Croft Rupert , Stanway Elizabeth R. , Bouwens Rychard J. , Thomas Peter
Published: February 2016

The Lyman-continuum photon production efficiency (ξion) is a critical ingredient for inferring the number of photons available to reionize the intergalactic medium. To estimate the theoretical production efficiency in the high-redshift Universe we couple the BlueTides cosmological hydrodynamical simulation with a range of stellar population synthesis models. We find Lyman-continuum photon production efficiencies of log10(ξion/erg−1 Hz) ≈ 25.1–25.5 depending on the choice of stellar population synthesis model. These results are broadly consistent with recent observational constraints at high-redshift though favour a model incorporating the effects of binary evolution.
Understanding inherited genetic risk of adult glioma – a
review
Authors: Rice Terri , Lachance Daniel H. , Molinaro Annette M. , Eckel-Passow Jeanette E. , Walsh Kyle M. , Barnholtz-Sloan Jill , Ostrom Quinn T. , Francis Stephen S. , Wiemels Joseph , Jenkins Robert B. , Wiencke John K. , Wrensch Margaret R.
Published: February 2016

During the past six years, researchers have made major progress identifying common inherited genetic variation that increases risk for primary adult glioma. This paper summarizes knowledge about rare familial cancer syndromes that include adult glioma and reviews the available literature on the more recently discovered common inherited variation. Ten independent inherited variants in eight chromosomal regions have been convincingly associated with increased risk for adult glioma. Most of these variants increase relative risk of primary adult glioma by 20% to 40%, but the TP53 variant rs78378222 confers a two-fold relative risk (ie, 200%), and rs557505857 on chromosome 8 confers a six-fold relative risk of IDH-mutated astrocytomas and oligodendroglial tumors (ie, 600%). Even with a six-fold relative risk, the overall risk of developing adult glioma is too low for screening for the high-risk variant on chromosome 8. Future studies will help clarify which inherited adult glioma risk variants are associated with subtypes defined by histology and/or acquired tumor mutations. This review also provides an information sheet for primary adult glioma patients and their families.
chromstaR: Tracking combinatorial chromatin state dynamics in space and time
Authors: Taudt Aaron , Nguyen Minh Anh , Heinig Matthias , Johannes Frank , Colomé-Tatché Maria
Published: February 2016

Background

Post-translational modifications of histone residue tails are an important component of genome regulation. It is becoming increasingly clear that the combinatorial presence and absence of various modifications define discrete chromatin states which determine the functional properties of a locus. An emerging experimental goal is to track changes in chromatin state maps across different conditions, such as experimental treatments, cell-types or developmental time points.

Results

Here we present chromstaR, an algorithm for the computational inference of combinatorial chromatin state dynamics across an arbitrary number of conditions. ChromstaR uses a multivariate Hidden Markov Model to determine the number of discrete combinatorial chromatin states using multiple ChIP-seq experiments as input and assigns every genomic region to a state based on the presence/absence of each modification in every condition. We demonstrate the advantages of chromstaR in the context of three common experimental data scenarios. First, we study how different histone modifications combine to form combinatorial chromatin states in a single tissue. Second, we infer genome-wide patterns of combinatorial state differences between two cell types or conditions. Finally, we study the dynamics of combinatorial chromatin states during tissue differentiation involving up to six differentiation points. Our findings reveal a striking sparcity in the combinatorial organization and temporal dynamics of chromatin state maps.

Conclusions

chromstaR is a versatile computational tool that facilitates a deeper biological understanding of chromatin organization and dynamics. The algorithm is implemented as an R-package and freely available fromhttp://bioconductor.org/packages/chromstaR/.
Translational plasticity facilitates the accumulation of nonsense genetic variants in the human population
Authors: Jagannathan Sujatha , Bradley Robert K.
Published: February 2016

Genetic variants that disrupt protein-coding DNA are ubiquitous in the human population, with ~100 such loss-of-function variants per individual. While most loss-of-function variants are rare, a subset have risen to high frequency and occur in a homozygous state in healthy individuals. It is unknown why these common variants are well-tolerated, even though some affect essential genes implicated in Mendelian disease. Here, we combine genomic, proteomic, and biochemical data to demonstrate that many common nonsense variants do not ablate protein production from their host genes. We provide computational and experimental evidence for diverse mechanisms of gene rescue, including alternative splicing, stop codon readthrough, alternative translation initiation, and C-terminal truncation. Our results suggest a molecular explanation for the mild fitness costs of many common nonsense variants, and indicate that translational plasticity plays a prominent role in shaping human genetic diversity.