bluuebunny/crossref_metadata_2025 huggingface dataset:
Proteome adaptations in Ethe1-deficient mice indicate a role in lipid catabolism and cytoskeleton organization via post-translational protein modifications
Authors: Hildebrandt Tatjana M. , Di Meo Ivano , Zeviani Massimo , Viscomi Carlo , Braun Hans-Peter
Published: June 2013

Hydrogen sulfide is a physiologically relevant signalling molecule. However, circulating levels of this highly biologically active substance have to be maintained within tightly controlled limits in order to avoid toxic side effects. In patients suffering from EE (ethylmalonic encephalopathy), a block in sulfide oxidation at the level of the SDO (sulfur dioxygenase) ETHE1 leads to severe dysfunctions in microcirculation and cellular energy metabolism. We used an Ethe1-deficient mouse model to investigate the effect of increased sulfide and persulfide concentrations on liver, kidney, muscle and brain proteomes. Major disturbances in post-translational protein modifications indicate that the mitochondrial sulfide oxidation pathway could have a crucial function during sulfide signalling most probably via the regulation of cysteine S-modifications. Our results confirm the involvement of sulfide in redox regulation and cytoskeleton dynamics. In addition, they suggest that sulfide signalling specifically regulates mitochondrial catabolism of FAs (fatty acids) and BCAAs (branched-chain amino acids). These findings are particularly relevant in the context of EE since they may explain major symptoms of the disease.
A Biomechanical Modeling Study of the Effects of the Orbicularis Oris Muscle and Jaw Posture on Lip Shape
Authors: Stavness Ian , Nazari Mohammad Ali , Perrier Pascal , Demolin Didier , Payan Yohan
Published: June 2013

Purpose

The authors' general aim is to use biomechanical models of speech articulators to explore how possible variations in anatomical structure contribute to differences in articulatory strategies and phone systems across human populations. Specifically, they investigated 2 issues: (a) the link between lip muscle anatomy and variability in lip gestures and (b) the constraints of coupled lip/jaw biomechanics on jaw posture in labial sounds.

Method

The authors used a model coupling the jaw, tongue, and face. First, the influence of the orbicularis oris (OO) anatomical implementation was analyzed by assessing how changes in depth (from epidermis to the skull) and peripheralness (proximity to the lip horn center) affected lip shaping. Second, the capability of the lip/jaw system to generate protrusion and rounding, or
labial closure
, was evaluated for different jaw heights.

Results

Results showed that a peripheral and moderately deep OO implementation is most appropriate for protrusion and rounding; a superficial implementation facilitates closure; protrusion and rounding require a high jaw position; and closure is achievable for various jaw heights.

Conclusions

Models provide objective information regarding possible links between anatomical and speech production variability across humans. Comparisons with experimental data will illustrate how motor control and cultural factors cope with these constraints.
High performance floating‐gate technology compatible antifuse
Authors: Xie Xiaodong , Li Wei , Li Jianjun , Wang Gang
Published: June 2013

An antifuse structure that is fully compatible with the standard floating‐gate technology is presented. The antifuse consists of an oxide‐nitride‐oxide dielectric layer, sandwiched between polysilicon and N‐well layers. The characteristics of the antifuse are investigated. The off‐state resistance of the antifuse is larger than 10 GΩ. The programmed antifuses show linear ohmic characteristics and have a tight resistance distribution centred around 350 Ω. The time dependent dielectric breakdown measurements show that the extrapolated lifetime of the unprogrammed antifuse at 5.5 V is as long as 40 years, and the resistance change of post‐program antifuses under the continuous reading mode test is lower than 5%.
MEMS‐based flexible capacitive electrode for ECG measurement
Authors: Wang Long‐Fei , Liu Jing‐Quan , Peng Hui‐Ling , Yang Bin , Zhu Hong‐Ying , Yang Chun‐Sheng
Published: June 2013

A thin and flexible capacitive electrode for recording an electrocardiogram (ECG) signal has been developed. Compared with the conventional wet electrode, the capacitive electrode can work without conductive gel and skin preparation, and serves as a tool of long‐term ECG measurement. The designed electrode consists of a sensing plate, an active shield plate and two insulating layers, which is fabricated by the micro‐electro‐mechanical system process. The test result shows that the capacitive electrode can obtain a high‐quality ECG signal that is comparable to the one recorded by the conventional wet electrode. The capacitive electrode can be arbitrarily bent to fit the human torso because of its extremely thin and flexible feature. Moreover, a simple front‐end circuit is used to integrate more easily into the measurement system.
Improved interference cancellation for downlink DCT‐MC‐CDMA systems
Authors: Al‐fuhaidi B.A. , Hassan H.E.A. , Salah M.M.
Published: June 2013

The low complexity receiver structure based on discrete cosine transform for a downlink multicarrier code division multiple access (DCT‐MC‐CDMA) system is proposed. It employs an interference cancellation scheme with a linear equaliser to suppress the multiple access interference and interference caused by the multipath fading channel The performance of the proposed receivers is analysed and compared to the conventional downlink DFT‐MC‐CDMA system. Simulation results show a large performance improvement when using such an interference cancellation scheme relative to the DCT equalisation receiver, and interference cancellation for the downlink DFT‐MC‐CDMA system.
Orthogonality‐based label correction in multi‐class classification
Authors: Xue H. , Chen S.
Published: June 2013

Orthogonality‐based label coding is an often‐used technique in multi‐class classification. Through coding the labels into some multi‐dimensional orthogonal codewords, many binary classifiers can be naturally extended to multi‐class cases. For an unseen sample, the classifiers firstly estimate its codeword and then compute the corresponding distances from the labels. Finally, the nearest one is assigned as its class label. However, these classifiers actually hardly guarantee that the estimated codewords still maintain the inter‐orthogonality with the other classes, which more likely causes the codewords in different classes overlapping each other to some extent and thus affects the classification performance. Proposed is a novel label correction strategy which aims to keep as much as possible orthogonality between the estimated sample codewords and the other classes’ labels in order to preserve further as much as possible the inter‐orthogonality of the codewords. The strategy is combined with two state‐of‐the‐art classifiers: regularised least square classifier and the least square support vector machine. Experiments on UCI datasets demonstrate the effectiveness of the method.
Error correction based Doppler estimation method for Doppler smearing
Authors: Zhang Z. , Li Y. , Zhang H.
Published: June 2013

An error correction based Doppler estimation method is first proposed to address the Doppler smearing problem in a low signal‐to‐noise ratio environment with a large Doppler acceleration. This method is shown to effectively increase the detection probability, and a closed‐form expression of net error correction probability is also derived.
Exact pre‐scheduling SINR analysis for per‐user unitary rate control systems
Authors: Lv Lei , Zhang ZhongPei
Published: June 2013

The exact probability density function (PDF) of the pre‐scheduling signal‐to‐interference‐plus‐noise ratio (SINR) for per‐user unitary rate control (PU2RC) systems is derived. A main contribution is proposing a novel dimension‐reducing‐type function to resolve the key problem, i.e. within a multi‐dimensional complex space, to obtain the PDF of a unit isotropic vector's maximum projection on vectors of an orthonormal basis. Even if PU2RC systems are only considered, the proposed function is quite useful for the analysis of other orthogonal beams‐based MIMO systems as well. Monte Carlo simulations validate the analysis results.
High peak power actively Q‐switched Ho3 +, Pr3 +‐co‐doped fluoride fibre laser
Authors: Hu T. , Hudson D.D. , Jackson S.D.
Published: June 2013

An actively Q‐switched diode‐pumped Ho3 +, Pr3 +‐co‐doped fluoride glass fibre laser operating in the first‐order diffraction mode is demonstrated. At a repetition a rate of 1 kHz, the laser produces pulses with a maximum peak power of 576 W and a pulse width of 33 ns at an average power of 19 mW at 2.87 µm.
Adapting sample size in particle filters through KLD‐resampling
Authors: Li T. , Sun S. , Sattar T.P.
Published: June 2013

An adaptive resampling method is provided. It determines the number of particles to resample so that the Kullback‐Leibler distance (KLD) between the distribution of particles before resampling and after resampling does not exceed a pre‐specified error bound. The basis of the method is the same as Fox's KLD‐sampling but implemented differently. The KLD‐sampling assumes that samples are coming from the true posterior distribution and ignores any mismatch between the true and the proposal distribution. In contrast, the KLD measure is incorporated into the resampling in which the distribution of interest is just the posterior distribution. That is to say, for sample size adjustment, it is more theoretically rigorous and practically flexible to measure the fit of the distribution represented by weighted particles based on KLD during resampling than in sampling. Simulations of target tracking demonstrate the efficiency of the method.
Human motion capture data recovery using trajectory‐based matrix completion
Authors: Tan Cheen‐Hau , Hou JunHui , Chau Lap‐Pui
Published: June 2013

Matrix completion has previously been used as a method to recover missing data in a mocap sequence. Improvments to this scheme by structuring motion capture data into an alternative representation for matrix completion are proposed. This representation takes advantage of the properties of mocap data and matrix completion to improve the reliability of matrix completion. Experiments show that the proposed motion capture data recovery method performs significantly better for nearly all tested motion sequences and amounts of missing data.
Dimensioning of dual leaky bucket parameters for regulating voice sources
Authors: Daigle J.N. , Femminella M. , Reali G.
Published: June 2013

An analytical approach to set the parameters of a dual leaky bucket for the purposes of regulating a voice over IP call at the network ingress is presented. The analytical model is used to determine the theoretical packet loss as a function of the dual leaky bucket parameters for traffic generated by a G.726 codec, then the theoretical packet loss is compared with that measured using a real voice conversation taking place over a Linux system and using an implementation of the G.726. The results are found to be in excellent agreement.
Reference spur suppression technique using ratioed current charge pump
Authors: Kamal N. , Al‐Sarawi S.F. , Abbott D.
Published: June 2013

Reference spurs are one of the main problems in integer‐N phase‐locked loops (PLLs). A ratioed current charge pump is proposed to suppress reference spur magnitude in the PLL output. The ratioed current charge pump can be implemented by resizing the source and drain network of the charge pump. A formula to calculate the ratioed current and transistor size is presented. The reference spur magnitude for a PLL with a ratioed current charge pump is compared to a conventional charge pump PLL, resulting in about 4 dBc/Hz improvement in the reference spur magnitude.
74 GHz, 17.2 dBm power amplifier in 45 nm SOI CMOS
Authors: Tai W. , Ricketts D.S.
Published: June 2013

A millimetre‐wave power amplifier (PA) fabricated in 45 nm SOI CMOS is reported that achieves 17.2 dBm saturated output power at 74 GHz without power combining using a 2.2 V supply, over twice the output power of previously reported single CMOS PAs. The peak gain and PAE are 14.3 dB and 11.1%, respectively. The PA also achieves a 3 dB bandwidth of 31 GHz while occupying a small die area of 0.23 mm2.
Two‐step continuous‐time incremental sigma–delta ADC
Authors: Tao S. , Rodriguez S. , Rusu A.
Published: June 2013

A two‐step continuous‐time (CT) incremental sigma–delta (IΣΔ) ADC, which enhances the performance of conventional CT IΣΔ ADCs, is proposed. By pipelining two second‐order CT IΣΔ ADCs, the proposed two‐step architecture can achieve high resolution without sacrificing the conversion rate. Compared to other alternatives, the two‐step CT IΣΔ ADC exhibits the freedom of adjusting its accuracy and speed independently while featuring quite relaxed circuit specifications.
Dual‐band bandpass filter based on CPW series‐connected resonators
Authors: Al‐Khateeb L. , Abu Safia O.
Published: June 2013

A new design of a three‐pole dual‐band bandpass filter using coplanar waveguide (CPW) series‐connected resonators and impedance inverters is proposed. The circuit conversions that lead to the lumped element model of the proposed filter are introduced. The resonators of the filter are implemented using special compact series‐connected resonators patterned in the centre conductor of a CPW transmission line. The filter operates at the two centre band frequencies 1.8 and 2.4 GHz. Hence, it is considered an excellent candidate for GSM/Wi‐Fi applications. Experimental results show very good agreement with simulated results, which validates the proposed filter.
Effects of extreme surface roughness on 3D printed horn antenna
Authors: Garcia C.R. , Rumpf R.C. , Tsang H.H. , Barton J.H.
Published: June 2013

3D printing is an emerging technology in manufacturing. It is the long‐term goal of the industry to print complex and fully functional products from cell phones to vehicles. A drawback of many 3D printing technologies is rough surface finish. It is known that metals with high surface roughness severely degrade the propagation of electromagnetic waves. Presented is the first known evaluation of the electromagnetic impact of the typical surface roughness in metal parts produced by electron beam melting. Two Ku‐band (12–15 GHz) horn antennas were 3D printed, with different surface roughness, and compared to a standard horn antenna purchased from Pasternack.
Size‐dependent photoluminescence in silicon nanostructures: quantum confinement effect
Authors: Kumar V. , Saxena K. , Shukla A.K.
Published: June 2013

Visible photoluminescence (PL) from laser‐etched silicon nanostructures has been analysed. A systematic size dependence study of PL from silicon nanostructures has been performed. The PL from these structures is attributed to the quantum confinement effect. Different quantum confinement models have been used for PL and Raman lineshape fitting to calculate the mean size and size distribution of silicon nanostructures and the results are comparatively studied. Calculated values of oscillator strength and radiative lifetime show that PL is due to radiative recombination of confined excitons.
Relative low‐temperature synthesis of lead titanate (PbTiO3) whiskers via flux method
Authors: Zhang Yongxing , Nai Xueying , Wei Ming , Bian Shaoju , Gao Dandan , Li Wu
Published: June 2013

Well dispersive and single‐crystal lead titanate (PbTiO3) whiskers were successfully synthesised by sintering lead acetate and titanium dioxide with improvement of adding potassium chloride as flux at a relatively low temperature. The starting materials were homogenised by different molar ratios and the as‐prepared samples were pre‐treated before characterising by X‐ray diffraction, a scanning electron microscope and a transmission electron microscope. Comparison experiments indicated that the temperature and the amount of flux played an important role in determining the morphology and purity of the products. A liquid–solid growth mechanism is proposed for formation of PbTiO3 whiskers.
Capillary phenomenon‐based pump‐less biochip for uric acid determination
Authors: Sakamoto Hiroaki , Hatsuda Ranko , Miyamura Kazuhiro , Sugiyama Susumu
Published: June 2013

In this reported study, the authors developed a uric acid biochip that does not require extra driving force. Although liquid flow is performed in a very narrow gap (2 μm), the capillary force is generated in this microfluidic device, which was fabricated from poly(methyl methacrylate) (PMMA) using a micromachining technique. The authors have fabricated a 2 μm pillar array through hot‐embossing and thermal bonding from a Si master mould. To increase the capillary force, the authors modified the PMMA surface by ultraviolet irradiation followed by poly‐L‐lysine coating. Electrodes were integrated into the microfluidic device to permit successful electrochemical measurement of uric acid with good reproducibility. This device also solves the problem of expenditure because of its potential scalability for mass production; although it is driven solely by capillary action, it does not require microfluidic pumps or any other additional power supply. The device is suitable for in situ analysis, diagnosis and house calls.
Magnetic biosensing system based on TSMC 0.35 um BioMEMS process for sensing magnetic nanobeads
Authors: Chung Wen Yaw , Ye Yi Ying , Uy Kimberly Jane , Yang Hao Chun
Published: June 2013

The demand for more compact devices has led to the growing demand for system‐on‐chip (SoC) devices. In this reported work a system has been designed that would target a specific protein by using antibodies for the capture and binding. By using the TSMC 0.35 μm bio‐microelectro‐mechanical systems (BioMEMS) technology, a SoC device that incorporates the sensor and readout circuit into one chip is achieved. The sensor system will be able to detect the quantity of the magnetic beads on the sensor surface. The gold layer from the BioMEMS process has high sensitivity for capturing and fixing the target antibodies on top of the sensor. The system consists of a front‐end sensing coil inductor and signal processor. The coil is used as the source of magnetic fields for magnetising the magnetic beads. Using a multiplexer to switch the sensor cells is a way to obtain the signal and infer the amount of the magnetic beads on a specific sensing region. Finally, UV epoxy was used to package the bonding wire of the sensor chip to make sure that biological fluids can directly drop onto the chip without short circuiting the system.
Surface modification of polydimethylsiloxane microchannel using air plasma for DNA capillary migration in polydimethylsiloxane–glass microfluidic devices
Authors: Alsadat Rad Maryam , Ibrahim Kamarulazizi , Mohamed Khairudin , Najimudin Nazalan
Published: June 2013

Polydimethylsiloxane (PDMS) microchannel surfaces were modified by air plasma to improve their applicability in microfluidics. The procedure included an increase in air plasma duration from 10 to 30 s. This resulted in an increase of wettability which was demonstrated by the decrease of water contact angles from 105° to 8°. The surface modification‐assisted PDMS microchannel easily bonded to a glass surface, and a PDMS/glass microfluidic device was fabricated with a simplified process. Slight pressure applied directly over the PDMS microchannel (approximate dimensions of 2.5 µm deep and 8.8 µm wide) formed nanoslits with dimensions of 830 nm in width and 170 nm in height on the PDMS/glass interface. Nanoslit formation was directly correlated to the metastable collapse of PDMS microchannels on the glass surface after the plasma treatment. The fabricated microfluidic devices were successfully employed for λ ‐DNA capillary migration without any external driving force.
Superhydrophobic zinc oxide film: effect of hybrid nanostructure on hydrophobicity and wetting stability
Authors: Wu Jun , Yang Xin , Lei Wei , Xia Jun , Wang Baoping
Published: June 2013

Superhydrophobic surfaces have been attracting research interest in the areas of self‐cleaning, drag reduction and fog condensation. However, many artificial superhydrophobic surfaces may be wetted under fluidic pressure and lose superhydrophobicity. To address this issue, the effect of surface morphologies on hydrophobicity and wetting stability should be investigated thoroughly. In this study, the authors describe a hybrid ZnO nanostructure which can be achieved by hydrothermal method. The hybrid nanostructure is constructed with a ZnO nanorods layer topped with a porous ZnO layer. The specific assembling format of the ZnO layers enhanced the stability of superhydrophobicity.
In situ synthesis of silver nanoparticles onto cotton fibres modified with plasma treatment and acrylic acid grafting
Authors: Haji Aminoddin , Barani Hossein , Qavamnia Sayyed Sadroddin
Published: June 2013

Silver nanoparticles were synthesised on the modified cotton fibres using an in situ method. Acrylic acid was grafted on the surface of cotton using plasma technology as a means to enhance the loading efficiency of nanoparticles. The loading efficiency of silver nanoparticles into the cotton fabric was examined by an atomic absorption spectrometer. The surface of the fibres was characterised by low‐voltage scanning electron microscopy and attenuated total reflection‐Fourier transform infrared spectrometry. The cotton fabrics loaded with Ag nanoparticles were examined by thermogravimetric analysis. In addition, the antibacterial activity of loaded samples was determined according to the AATCC test method 147‐2004. Grafting of acrylic acid on cotton fibre leads to increase in the loading efficiency of silver nanoparticles and this sample showed the highest antibacterial activity.
Modelling and simulation of dynamic modes in manipulation of nanorods
Authors: Korayem M. H. , Hoshiar A. K.
Published: June 2013

The use of atomic force microscopy (AFM)‐based robots for moving cylindrical particles has become the focus of attention in recent research works. The impossibility of observing the moving process during motion has highlighted the role of computer simulation in the investigation of nanoparticles’ movement. The motion modes (sliding, rolling, spinning) are used to investigate the mode by which a particle moves on a substrate. By using the presented model it is possible to simulate the conditions under which each of these modes are created. To validate the results, it has been observed that by gradual reduction of the nanorod's length, the obtained results are more similar to the results of the spherical case. Furthermore, the presented modes have been evaluated by comparing with the experimental findings, which shows adequate compatibility and acceptable accuracy. In this Letter, first, the movement of particles is modelled and then the effective parameters of the process are simulated. Afterwards, the simulation of dynamic modes is carried out and, finally, verification of the results is presented. By using the presented simulations, it would be possible to predict the mode of movement during the manipulation of nanorods by means of AFM nanorobots.
Numerical simulation of a plasma actuator based on ion transport
Authors: Yamamoto Seiya , Fukagata Koji
Published: June 2013

Two-dimensional numerical simulation of ion transport and flow around a single dielectric barrier discharge plasma actuator (PA) is performed. Spatial distributions of ions and electrons as well as their time evolution are obtained by solving the transport equations of monovalent positive ions, monovalent negative ions, and electrons. Voltage and frequency of the driving alternating-current signal are assumed to be 8 kV and 5 kHz, respectively. Special focus is laid upon the effect of voltage gradient dV/dt on the magnitude of the body force. The validity of steady force models often used in flow simulation is also examined. The simulation results show that the magnitude of the body force induced by the PA increases as the voltage gradient dV/dt increases and its increase rate becomes milder at higher voltage. The mechanism of body force generation is explained from the time evolution of number density fields of ions and electrons. A comparison between flow simulations using a time-resolved body force and its time-averaged counterpart demonstrates that the time-averaged model gives sufficiently accurate results when the time scale of the flow is more than 30 times greater than that of the PA.
Scaling of hysteresis loop of interacting polymers under a periodic force
Authors: Mishra Rakesh Kumar , Mishra Garima , Giri Debaprasad , Kumar Sanjay
Published: June 2013

Using Langevin dynamics simulations, we study a simple model of interacting-polymer under a periodic force. The extension curves strongly depend on the magnitude of the amplitude (F) and the frequency (ν) of the applied force. In low frequency limit, the system retraces the thermodynamic path. At higher frequencies, response time is greater than the external time scale for change of force, which restrict the biomolecule to explore a smaller region of phase space that results in hysteresis of different shapes and sizes. We show the existence of dynamical transition, where area of hysteresis loop approaches to a large value from nearly zero value with decreasing frequency. The area of hysteresis loop is found to scale as Fανβ for the fixed length. These exponents are found to be the same as of the mean field values for a time dependent hysteretic response to periodic force in case of the isotropic spin.
Covariant differential identities and conservation laws in metric-torsion theories of gravitation. I. General consideration
Authors: Lompay Robert R. , Petrov Alexander N.
Published: June 2013

Arbitrary diffeomorphically invariant metric-torsion theories of gravity are considered. It is assumed that Lagrangians of such theories contain derivatives of field variables (tensor densities of arbitrary ranks and weights) up to a second order only. The generalized Klein-Noether methods for constructing manifestly covariant identities and conserved quantities are developed. Manifestly covariant expressions are constructed without including auxiliary structures like a background metric. In the Riemann-Cartan space, the following manifestly generally covariant results are presented: (a) The complete generalized system of differential identities (the Klein-Noether identities) is obtained. (b) The generalized currents of three types depending on an arbitrary vector field displacements are constructed: they are the canonical Noether current, symmetrized Belinfante current, and identically conserved Hilbert-Bergmann current. In particular, it is stated that the symmetrized Belinfante current does not depend on divergences in the Lagrangian. (c) The generalized boundary Klein theorem (third Noether theorem) is proved. (d) The construction of the generalized superpotential is presented in detail, and questions related to its ambiguities are analyzed.
Invited Article: A test-facility for large-area microchannel plate detector assemblies using a pulsed sub-picosecond laser
Authors: Adams Bernhard , Chollet Matthieu , Elagin Andrey , Oberla Eric , Vostrikov Alexander , Wetstein Matthew , Obaid Razib , Webster Preston
Published: June 2013

The Large Area Picosecond Photodetector Collaboration is developing large-area fast photodetectors with time resolution ≲10 ps and space resolution ≲1 mm based on atomic layer deposition-coated glass Micro-Channel Plates (MCPs). We have assembled a facility at Argonne National Laboratory for characterizing the performance of a wide variety of microchannel plate configurations and anode structures in configurations approaching complete detector systems. The facility consists of a pulsed Ti:Sapphire laser with a pulse duration ≈100 fs, an optical system allowing the laser to be scanned in two dimensions, and a computer-controlled data-acquisition system capable of reading out 60 channels of anode signals with a sampling rate of over 10 GS/s. The laser can scan on the surface of a sealed large-area photodetector, or can be introduced into a large vacuum chamber for tests on bare 8 in.-square MCP plates or into a smaller chamber for tests on 33-mm circular substrates. We present the experimental setup, detector calibration, data acquisition, analysis tools, and typical results demonstrating the performance of the test facility.
Light tunneling effect tuned by a meta-interface with electromagnetically-induced-transparency-like properties
Authors: Feng Tuanhui , Yang Fei , Li Yunhui , Sun Yong , Lu Hai , Jiang Haitao , Zhang Yewen , Chen Hong
Published: June 2013

In this letter, light tunneling effect tuned by a meta-interface with electromagnetically-induced-transparency-like (EIT-like) properties is investigated. Both numerical and experimental results show that the Q-factor of tunneling mode can be well enhanced when an atomic-like three-level system with EIT-like properties is introduced at the interface of a pair structure constructed by epsilon-negative and mu-negative metamaterials. Further study reveals that the Q-factor can be tuned conveniently by altering the EIT-like meta-interface. Moreover, these advantages are not at costs of increase of volume and drastic reduction of transmittance.
A constitutive framework for the non-Newtonian pressure tensor of a simple fluid under planar flows
Authors: Hartkamp Remco , Todd B. D. , Luding Stefan
Published: June 2013

Non-equilibrium molecular dynamics simulations of an atomic fluid under shear flow, planar elongational flow, and a combination of shear and elongational flow are unified consistently with a tensorial model over a wide range of strain rates. A model is presented that predicts the pressure tensor for a non-Newtonian bulk fluid under a homogeneous planar flow field. The model provides a quantitative description of the strain-thinning viscosity, pressure dilatancy, deviatoric viscoelastic lagging, and out-of-flow-plane pressure anisotropy. The non-equilibrium pressure tensor is completely described through these four quantities and can be calculated as a function of the equilibrium material constants and the velocity gradient. This constitutive framework in terms of invariants of the pressure tensor departs from the conventional description that deals with an orientation-dependent description of shear stresses and normal stresses. The present model makes it possible to predict the full pressure tensor for a simple fluid under various types of flows without having to produce these flow types explicitly in a simulation or experiment.
Single element Raman thermometry
Authors: Saltonstall Christopher B. , Serrano Justin , Norris Pamela M. , Hopkins Patrick E. , Beechem Thomas E.
Published: June 2013

Despite a larger sensitivity to temperature as compared to other microscale thermometry methods, Raman based measurements typically have greater uncertainty. In response, a new implementation of Raman thermometry is presented having lower uncertainty while also reducing the time and hardware needed to perform the experiment. Using a modulated laser to excite the Raman response, the intensity of only a portion of the total Raman signal is leveraged as the thermometer by using a single element detector monitored with a lock-in amplifier. Implementation of the lock-in amplifier removes many sources of noise that are present in traditional Raman thermometry where the use of cameras preclude a modulated approach. To demonstrate, the portion of the Raman spectrum that is most advantageous for thermometry is first identified by highlighting, via both numerical prediction and experiment, those spectral windows having the largest linear dependence on temperature. Using such windows, the new technique, termed single element Raman thermometry (SERT), is utilized to measure the thermal profile of an operating microelectromechanical systems (MEMS) device and compared to results obtained with a traditional Raman approach. The SERT method is shown to reduce temperature measurement uncertainty by greater than a factor of 2 while enabling 3 times as many data points to be taken in an equal amount of time as compared to traditional Raman thermometry.
Medium-range topological constraints in binary phosphate glasses
Authors: Rodrigues B. P. , Wondraczek L.
Published: June 2013

The theory of temperature-dependent topological constraints has been used to successfully explain the compositional dependence of glass properties for oxide and non-oxide compositions. However, even though the predictions are qualitatively accurate, not all quantitative predictions are as precise. Here, we report on the applications of this theoretical framework to available data for binary phosphate and silver metaphosphate – silver halide glasses. We find that some compositions are overconstrained and some are underconstrained relative to the predicted values. We suggest that the origin of this difference is due to the presence of medium-range constraints such as sterical hindrance which is dependent on packing density and chain length.
Electromagnetically induced interference in a superconducting flux qubit
Authors: Du Lingjie , Yu Yang , Lan Dong
Published: June 2013

Interaction between quantum two-level systems (qubits) and electromagnetic fields can provide additional coupling channels to qubit states. In particular, the interwell relaxation or Rabi oscillations, resulting, respectively, from the multi- or single-mode interaction, can produce effective crossovers, leading to electromagnetically induced interference in microwave driven qubits. The environment is modeled by a multimode thermal bath, generating the interwell relaxation. Relaxation induced interference, independent of the tunnel coupling, provides deeper understanding to the interaction between the qubits and their environment. It also supplies a useful tool to characterize the relaxation strength as well as the characteristic frequency of the bath. In addition, we demonstrate the relaxation can generate population inversion in a strongly driving two-level system. On the other hand, different from Rabi oscillations, Rabi-oscillation-induced interference involves more complicated and modulated photon exchange thus offers an alternative means to manipulate the qubit, with more controllable parameters including the strength and position of the tunnel coupling. It also provides a testing ground for exploring nonlinear quantum phenomena and quantum state manipulation in qubits either with or without crossover structure.
Fermi resonance in Ne, Ar and Kr-matrix infrared spectra of 5-bromouracil
Authors: Ivanov A. Yu. , Rubin Yu. V. , Egupov S. A. , Belous L. F. , Karachevtsev V. A.
Published: June 2013

Low-temperature matrix isolation Fourier-transform infrared spectroscopy and quantum-chemical calculations with DFT/B3LYP and MP2 methods were used for investigation of isolated 5-bromouracil (BrU) molecules. Only one tautomeric form of BrU was dominated in the low-temperature Ne, Ar, and Kr matrices. It was revealed that population of minor hydroxy-tautomers did not exceed 0.2%. Appearance of additional absorption bands in the region of stretching vibrations νCO (about 1710 cm−1) as well as of deformation ones (1297, 1093, 901 cm−1) was explained by Fermi resonance. In Ne matrices the peak intensities of absorption bands assigned to the out-of-plane vibrations of the ring and exocyclic atoms were decreased sharply. For the first time, least square method with the using of polynomial was proposed for the corrective scaling of calculated frequencies of vibrations. It is shown that the correction of calculated frequencies with the polynomial of degree two permits to decrease the root-mean-square discrepancy between the calculated and experimental ones to 4–5 cm−1 in the region of 1500–500 cm−1. The same polynomial may be applied for the correction of spectra of molecules with a similar structure.
Reactivity of free radical intermediates that form spontaneously during molecular chlorine action on acetylene and vinyl monomers at low temperatures
Authors: Gordon D. A. , Volodina V. A. , Mikhailov A. I.
Published: June 2013

In this study, ESR, UV, VIS and IR spectroscopy, as well as chromatography, calorimetry, and elemental analysis were employed to show the spontaneous formation of free radicals under low-temperature action of molecular chlorine on acetylene monomer p-diethynylbenzene and on vinyl monomer acrylamide. These radicals are able to initiate a chain reaction of polymerization of monomers at low temperatures. This reaction results in a completely soluble polymer with a 25% yield, while an insoluble cross-linked polymer has been obtained during polymerization of p-diethynylbenzene initiated by other means. For example, under radiolysis by 1000 kGy the soluble fraction of obtained polymer was ≈1%, while the overall yield was ≈10%. p-Diethynylbenzene polymerizes at temperatures close to the melting temperature of chlorine (170 K). Polymerization of acrylamide takes place in the temperature range of 180–210 K with a ≈10% yield of polymer. The low-temperature chlorination of a 20% solution of acrylamide in glycerol enables a twofold increase of the polymer yield and a tenfold decrease of the chlorine content in it.
Rate equation approach to understanding the ion-catalyzed formation of peptides
Authors: Dubrovskii V. G. , Sibirev N. V. , Eliseev I. E. , Vyazmin S. Yu , Boitsov V. M. , Natochin Yu. V. , Dubina M. V.
Published: June 2013

The salt-induced peptide formation is important for assessing and approaching schemes of molecular evolution. Here, we present experimental data and an exactly solvable kinetic model describing the linear polymerization of L-glutamic amino acid in water solutions with different concentrations of KCl and NaCl. The length distributions of peptides are well fitted by the model. Strikingly, we find that KCl considerably enhances the peptide yield, while NaCl does not show any catalytic effect in most cases under our experimental conditions. The greater catalytic effect of potassium ions is entirely interpreted by one and single parameter, the polymerization rate constant that depends on the concentration of a given salt in the reaction mixture. We deduce numeric estimates for the rate constant at different concentrations of the ions and show that it is always larger for KCl. This leads to an exponential increase of the potassium- to sodium-catalyzed peptide concentration ratio with length. Our results show that the ion-catalyzed peptides have a higher probability to emerge in excess potassium rather than in sodium-rich water solutions.
Relative equilibria of point vortices on the hyperbolic sphere
Authors: Hwang Seungsu , Kim Sun-Chul
Published: June 2013

Relative equilibria of point vortices on a hyperbolic sphere with constant negative curvature is formulated and considered. Known symmetries for the vortex motion on the hyperbolic sphere are expounded by setting up a geometrical formulation of dynamics. In particular, the configuration of rings of vortices is investigated in detail.
Construction of concrete orthonormal basis for (L2, Γ, χ)-theta functions associated to discrete subgroups of rank one in $({\mathbb {C}},+)$(C,+)
Authors: Ghanmi Allal , Intissar Ahmed
Published: June 2013

For given rank one discrete subgroup \documentclass[12pt]{minimal}\begin{document}$\Gamma =\mathbb {Z}$\end{document}Γ=Z of the additive group \documentclass[12pt]{minimal}\begin{document}$(\mathbb {C},+)$\end{document}(C,+) and given character χ on it, we construct a complete orthonormal basis of the Hilbert space of \documentclass[12pt]{minimal}\begin{document}$(L^2,\mathbb {Z},\chi )$\end{document}(L2,Z,χ)-theta functions. A Hilbertian orthogonal decomposition involving the L2-eigenspaces of the Landau operator is given. Corresponding orthonormal basis are constructed and the corresponding reproducing kernel can be expressed in terms of the generalized theta function of characteristic [α, 0]. In particular, the Hilbert subspace of entire \documentclass[12pt]{minimal}\begin{document}$(L^2,\mathbb {Z},\chi )$\end{document}(L2,Z,χ)-theta functions coincides with the null space (the L2-eigenspace associated to the lowest eigenvalue). Furthermore, a periodic analog of Segal-Bargmann transform is obtained by introducing special integral transform, with a theta-kernel, mapping the L2-sections of a line bundle on the circle \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}/\mathbb {Z}$\end{document}R/Z to holomorphic sections of a line bundle on \documentclass[12pt]{minimal}\begin{document}$\mathbb {C}/\mathbb {Z}$\end{document}C/Z.
Relaxation of enthalpy fluctuations during sub-Tg annealing of glassy selenium
Authors: Gulbiten Ozgur , Mauro John C. , Lucas Pierre
Published: June 2013

The relaxation behavior of glass is influenced by the presence of dynamical heterogeneities, which lead to an intrinsically non-monotonic decay of fluctuations in density and enthalpy during isothermal annealing. This is apparently a universal feature of fragile glass forming systems associated with localized spatial variations in relaxation time. Here we present direct experimental observation of the nonmonotonic evolution of enthalpy fluctuations in glassy selenium annealed near room temperature. The nonmonotonic change in the distribution of enthalpy fluctuations measured by heat capacity spectroscopy offers direct evidence for the presence of dynamical heterogeneity in this glass. An enthalpy landscape model of selenium is then used to simulate annealing under identical conditions. The simulation results closely follow the evolution of enthalpy fluctuations observed experimentally. The close match between model and experiment demonstrate that enthalpy and density fluctuations are sources of dynamical heterogeneities in glassy materials.
Classical nucleation theory from a dynamical approach to nucleation
Authors: Lutsko James F. , Durán-Olivencia Miguel A.
Published: June 2013

It is shown that diffusion-limited classical nucleation theory (CNT) can be recovered as a simple limit of the recently proposed dynamical theory of nucleation based on fluctuating hydrodynamics [J. F. Lutsko, J. Chem. Phys. 136, 034509 (2012)]10.1063/1.3677191. The same framework is also used to construct a more realistic theory in which clusters have finite interfacial width. When applied to the dilute solution/dense solution transition in globular proteins, it is found that the extension gives corrections to the nucleation rate even for the case of small supersaturations due to changes in the monomer distribution function and to the excess free energy. It is also found that the monomer attachment/detachment picture breaks down at high supersaturations corresponding to clusters smaller than about 100 molecules. The results also confirm the usual assumption that most important corrections to CNT can be achieved by means of improved estimates of the free energy barrier. The theory also illustrates two topics that have received considerable attention in the recent literature on nucleation: the importance sub-dominant corrections to the capillary model for the free energy and of the correct choice of the reaction coordinate.
Kinetics of receptor occupancy during morphogen gradient formation
Authors: Berezhkovskii Alexander M. , Shvartsman Stanislav Y.
Published: June 2013

During embryogenesis, sheets of cells are patterned by concentration profiles of morphogens, molecules that act as dose-dependent regulators of gene expression and cell differentiation. Concentration profiles of morphogens can be formed by a source-sink mechanism, whereby an extracellular protein is secreted from a localized source, diffuses through the tissue and binds to cell surface receptors. A morphogen molecule bound to its receptor can either dissociate or be internalized by the cell. The effects of morphogens on cells depend on the occupancy of surface receptors, which in turn depends on morphogen concentration. In the simplest case, the local concentrations of the morphogen and morphogen-receptor complexes monotonically increase with time from zero to their steady-state values. Here, we derive analytical expressions for the time scales which characterize the formation of the steady-state concentrations of both the diffusible morphogen molecules and morphogen-receptor complexes at a given point in the patterned tissue.
Measurement of XeI and XeII velocity in the near exit plane of a low-power Hall effect thruster by light induced fluorescence spectroscopy
Authors: Dancheva Y. , Biancalana V. , Pagano D. , Scortecci F.
Published: June 2013

Near exit plane non-resonant light induced fluorescence spectroscopy is performed in a Hall effect low-power Xenon thruster at discharge voltage of 250 V and anode flow rate of 0.7 mg/s. Measurements of the axial and radial velocity components are performed, exciting the \documentclass[12pt]{minimal}\begin{document}$6s ^2[3/2]^o_2\rightarrow 6p ^2[3/2]_2$\end{document}6s2[3/2]2o→6p2[3/2]2 transition at 823.16 nm in XeI and the \documentclass[12pt]{minimal}\begin{document}$5d [4]_{7/2}\rightarrow 6p [3]^o_{5/2}$\end{document}5d[4]7/2→6p[3]5/2o transition at 834.724 nm in XeII. No significant deviation from the thermal velocity is observed for XeI. Two most probable ion velocities are registered at a given position with respect to the thruster axis, which are mainly attributed to different areas of creation of ions inside the acceleration channel. The spatial resolution of the set-up is limited by the laser beam size (radius of the order of 0.5 mm) and the fluorescence collection optics, which have a view spot diameter of 8 mm.
A current-carrying coil design with improved liquid cooling arrangement
Authors: Ricci Leonardo , Martini Luca Matteo , Franchi Matteo , Bertoldi Andrea
Published: June 2013

The design of an electromagnet requires the compliance with a number of constraints such as power supply characteristics, coil inductance and resistance, and, above all, heat dissipation, which poses the limit to the maximum achievable magnetic field. A common solution consists in using copper tubes in which a coolant flows. This approach, however, introduces further hydrodynamic concerns. To overcome these difficulties, we developed a new kind of electromagnet in which the pipe concept is replaced by a duct formed by the windings. Here we report on the realization and characterization of a compact model system in which the conductors carry a current that is one order of magnitude higher than the current allowable with conventional designs.
The effect of preionization on the shock wave evolution in a fast cylindrical discharge
Authors: Antsiferov P. S. , Dorokhin L. A.
Published: June 2013

The present work is devoted to the study of the properties of the shock wave, appearing in a fast cylindrical discharge (dI/dt about 1012 A/s). The phenomenon under study is the influence of the preionization current (about 500 A) upon the evolution of the shock wave. The discharge was produced in an alumina tube with inner diameter 6 mm, filled with argon to pressures ranging from 80 to 320 Pa. The shock wave was detected from the vacuum ultra violet emission of the hot plasma behind the front, using a pin-hole camera and a microchannel plate detector with a gating time of 10 ns. The measured velocities of the shock wave front are in the range (1–4) × 106 cm/s. The main effect of the preionization is the earlier start of the shock wave from the inner surface of the alumina discharge tube and about 1.5 times increase of the velocity of the front. The time delay of the shock wave cumulation in the absence of the preionization results in the appearance of the eroded wall material in the plasma.