bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimised projections for generalised distributed compressed sensing
Authors: Zhang Qiheng , Fu Yuli , Li Haifeng , Rong Rong
Published: March 2014

Different signals from the various sensors of the same scene form an ensemble. Distributed compressed sensing (DCS) rests on a new concept called the joint sparsity of the ensemble. JSM‐1 is a model that describes the joint sparsity by one dictionary. Previously, the generalisation of JSM‐1 was proposed where the signal ensemble depends on two dictionaries. Its compressed sensing (CS) version is considered: generalised DCS (GDCS). Instead of using random projections (random Gaussian (rGauss)), a gradient method with Barzilai–Borwein stepsize (GBB) is developed to optimise the projections in the GDCS. It enhances the reconstruction performance of the GDCS. It is verified by some experiments on the synthesised signals.
Wearable dual‐band composite right/left‐handed waveguide textile antenna for WLAN applications
Authors: Yan Sen , Soh Ping Jack , Vandenbosch Guy A.E.
Published: March 2014

An innovative, flexible, planar waveguide antenna operating in dual‐band mode for WLAN applications is proposed. This antenna has a simple topology, is compact and is easy to manufacture fully using textiles. It involves loading by a composite right/left‐handed waveguide to generate similar radiation patterns and low backward radiation in both operating bands. The latter property is extremely desirable for wearable applications as it avoids performance degradation due to dielectric coupling to the body, besides reducing possible health risks. Simulated and measured results indicate a good reflection and radiation performance agreement in both the 2.45 and the 5.4 GHz WLAN bands.
Scalable CMOS power combiner
Authors: Ren Zhixiong , Zhang Kefeng , Chen Xiaofei , Liu Zhenglin
Published: March 2014

A new power combiner consisting of four quarter‐circle transmission line transformers is presented for realising the full integration of CMOS power amplifiers (PAs) Full‐wave electromagnetic simulation confirms the scalability with size and technology of the combiner without efficiency degeneration.
Segmenting dark channel prior in single image dehazing
Authors: Bui T.M. , Tran H.N. , Kim W. , Kim S.
Published: March 2014

In image dehazing, the existing transmission estimators bring out the halo artefact at boundaries unless they adopt a refinement procedure with a high computational complexity. How the existing transmission estimation methods suffer from the halo artefact at the boundaries are analysed and it is found that the elaborate, high computational refinement procedure to remove the halo effect are excessive for dehazing. On the basis of the above‐mentioned analysis and finding, a simple segmentation logic was embedded in an existing transmission estimator, which is sufficiently accurate for dehazing. The experiment verifies that the proposed method significantly reduces the halo artefact without requiring any refinement procedure.
Polarisation‐independent beam scanner using electro‐optic KTN crystals
Authors: Toyoda S. , Miyazu J. , Sasaki Y. , Imai T. , Kobayashi J.
Published: March 2014

A polarisation‐independent optical beam scanner that uses electro‐optic KTa1−xNbxO3 (KTN) crystals has been demonstrated. The polarisation dependence was compensated for by using a pair of KTN beam scanners and a half‐waveplate without any degradation in the performance of either KTN beam scanner. This compensation is the result of a combination of electro‐optic effects consisting of Kerr effects and elasto‐optic effects via the electrostrictive and elastic strains in KTN crystals.
Relaxing CFL limit of FDTD by DWT
Authors: Sun Zheng , Shi Li‐Hua , Zhou Ying‐Hui
Published: March 2014

To extend the Courant‐Friedrichs‐Lewy (CFL) limit, a discrete wavelet transform (DWT) is incorporated into the finite difference time domain (FDTD) scheme. With the Mallat algorithm for the decomposition and reconstruction of the electromagnetic components, the unstable spatial modes can be efficiently filtered out. Consequently, the original strict CFL limit of the FDTD can be significantly relaxed, and much execution time can be saved. The performance and versatility of the proposed method is demonstrated by the numerical examples.
Low‐complexity data decoding using binary phase detection in SLM‐OFDM systems
Authors: Adegbite S.A. , McMeekin S.G. , Stewart B.G.
Published: March 2014

High computational complexity associated with maximum‐likelihood (ML) data decoding in orthogonal frequency division multiplexing (OFDM) systems that use selected mapping (SLM) for the reducing peak‐to‐average power ratio (PAPR) can be significantly reduced using modified SLM and data decoding techniques presented in this Letter. Simulations show that the proposed method achieves similar PAPR reduction capability and data recovery performance compared with standard SLM (with perfect data recovery) and an ML detection scheme.
Adaptive equalisation using particle swarm optimisation for uplink SC‐FDMA
Authors: Iqbal N. , Zerguine A. , Al‐Dhahir N.
Published: March 2014

An adaptive frequency‐domain equaliser for the single carrier frequency division multiple access (SC‐FDMA) system using the particle swarm optimisation (PSO) technique is proposed. Unlike the stochastic gradient and recursive least squares algorithms, the PSO is known to have fast convergence which does not depend on the underlying structure. The cost function used in a PSO is formulated based on the respective structure of the equaliser, whether it is a linear equaliser or a decision feedback equaliser. The robustness of the proposed PSO algorithm is demonstrated on a high Doppler scenario. Furthermore, it is shown that the performance improves more when using re‐randomisation. Finally, it is shown that the PSO‐based frequency‐domain equaliser is more computationally efficient than its time‐domain counterpart.
Broadcast‐based data delivery strategy for V2I multihop vehicular networks
Authors: Suh Bongsue , Berber S.
Published: March 2014

A new strategy to reduce data delivery delay for vehicle‐to‐infrastructure (V2I) communication systems with multiple stationary roadside units (RSUs) is proposed. With the proposed strategy, the data delivery is accomplished through vehicles possessing identical packets received via broadcasting from an RSU, and the group of the packet‐possessing vehicles is refreshed at each RSU hop. Numerical results show that the proposed strategy reduces the data delivery delay compared with an existing strategy and does so more significantly for a middle‐range traffic density. In addition, the proposed strategy has better performance as the broadcast duration and the RSU's coverage area increase.
Occlusion‐adaptive bidirectional motion compensation for pixel‐based motion vector field
Authors: Lu Qingchun , Fang Xiangzhong , Wang Ci
Published: March 2014

An occlusion‐adaptive bidirectional motion compensation method using pixel‐based motion vectors that reduces ghost artefacts due to occlusion is proposed. The proposed method constructs each pixel in the intermediated frame as a weighted average of its motion‐compensated pixel candidates. The weighting factor for each pixel candidate is determined adaptively by utilising a temporal motion consistency metric. Moreover, a local support window mechanism is presented in bidirectional interpolation to enhance the intensity transition smoothness among neighbouring pixels. Experimental results demonstrate that the proposed method can effectively improve the quality of the interpolated frames without annoying visual artefacts.
Image quality assessment scheme with topographic independent components analysis for sparse feature extraction
Authors: Ding Yong , Dai Hang , Wang Shaoze
Published: March 2014

A no‐reference objective metric for image quality assessment by integrating the topographic independent components analysis into feature extraction is presented. By taking the topographic relationship among the initially independent features into consideration, it extracts the features of more sparsity or independency which is essentially related to inherent quality. Evaluation results demonstrate that the proposed metric is able to predict the image quality accurately across various distortion types.
Design of low‐phase‐noise CMOS transformer‐based gate‐coupled quadrature VCO
Authors: Shen Yi , Tsang K.F. , Lee Wah Ching , Hung Faan Hei , Triantis Iasonas F. , Xuan Kai
Published: March 2014

A low‐phase‐noise transformer‐based gate‐coupled quadrature voltage‐controlled oscillator (TGC‐QVCO) using 0.13 μm CMOS technology is presented. The TGC‐QVCO consumes 7 mW at 1 V power supply with 18% frequency tuning. The measured phase noise at 1 MHz offset varies from about −122 to −119 dBc/Hz for frequency tuning from 1.34 to 1.6 GHz. The achieved figure of merit (FoM) is 179 dB and the chip area is 800 × 900 μm2.
Miniaturised 43 Gbit/s ROSA module using TO‐can package for optical transceivers
Authors: Kang Sae‐Kyoung , Lee Joon Ki , Huh Joon Young , Kim KwangJoon , Lee Jong Hyun
Published: March 2014

A 43 Gbit/s receiver optical subassembly (ROSA) module using a compact transistor outline‐can (TO‐can) package has been developed and successfully demonstrated at transmission over a 2 km single‐mode fibre. The electrical interface of the ROSA is made of an impedance‐matched flexible printed circuit board (FPCB) which is orthogonally connected to the TO‐can package. The measured 3 dB optical‐to‐electrical bandwidth is ∼31.5 GHz and the receiver sensitivity is <−8.4 dBm at an extinction ratio of 8.2 dB and a bit error rate of 10−12.
LUT‐oriented dual‐rail quasi‐delay‐insensitive logic synthesis
Authors: Lemberski I.
Published: March 2014

The method of quasi‐delay‐insensitive logic synthesis using look‐up tables (LUTs) is described. It is shown that the dual‐rail sum‐of‐minterm function hazard‐free implementation can be done using a single LUT. Namely, instead of the conventional approach based on a DIMS representation where each minterm is implemented on a C‐element, the whole sum‐of‐minterm function is mapped into the single C‐element. For Boolean network implementation, it is proved that a fork with branches to different nodes is not required to be isochronic. It simplifies technological synthesis and allows using existing placement and routine methods and tools supposed for synchronous logic. Compared to the conventional approach, the method reduces significantly circuit complexity (in terms of the number of LUTs).
Adaptation of hidden Markov model mean parameters using two‐dimensional PCA with constraint on speaker weight
Authors: Jeong Yongwon
Published: March 2014

A basis‐based speaker adaptation technique is proposed, where basis vectors are derived using two‐dimensional principal component analysis (2DPCA) and the speaker weight for the target speaker is constrained in the space of training speaker weights. During adaptation, the speaker weight that is derived in the maximum‐likelihood framework is constrained by projecting the weight into the space of the weights of training speakers. In the experiments, the proposed approach shows performance improvement over the unconstrained 2DPCA‐based approach.
Docking control on both stationary and moving stations based on docking formation
Authors: Kwon Ji‐Wook , Seo Jiwon
Published: March 2014

A docking control algorithm of a non‐holonomic mobile agent is proposed, which can be employed in both the stationary and the underway docking stations. To this end, a leader–follower docking formation is proposed, where the size of the formation is reduced until docking surfaces of the agent and the docking stations contact each other. Also, a feedback linearisation control law that can compensate for the input constraint is implemented to maintain the docking formation. Numerical simulations are included to show the performance of the proposed docking control algorithm.
Femtosecond laser‐written waveguides in thulium‐doped fluoroindate glass for S‐band amplification
Authors: Elan F. , Olivero M. , Falcão‐Filho E.L. , de Araújo C.B. , Messaddeq Y. , Gomes A.S.L.
Published: March 2014

Channel waveguides were written in a fluoroindate bulk glass containing thulium, with a femtosecond laser operating at 800 nm, 100 fs pulses and a repetition rate of 1 kHz. Formation of waveguides occurred for average powers from 1 to 8 mW (corresponding to energies of 1–8 μJ) and scan velocities in the range of 0.1–4 mm/s. Passive optical characterisation included visual inspection by an optical microscope, insertion loss and mode profile. Active characterisation was performed by co‐propagating pumping in a dual‐pump scheme that included an 808 nm and a 1054 nm laser diode for an efficient inversion of the 3H4 level, which is responsible for stimulated emission in the 1460–1530 nm spectral range. Preliminary tests show a net gain of 2.5 dB at 1487 nm, for straight waveguides 1 cm long. Applications include the fabrication of lossless components working in the S‐band region of the optical communication spectrum.
Radiofrequency inductive probe for non‐contact dielectric characterisations of organic medium
Authors: Masilamany G. , Joubert P.‐Y. , Serfaty S. , Roucaries B. , Le Diraison Y.
Published: March 2014

A high sensitivity radiofrequency (RF) probe dedicated to contactless dielectric characterisations is presented. A method for the impedance measurement of a distant RF resonator is first proposed. The method is evaluated as a function of the measurement distance starting from experiments. The obtained results enable assessment of the accuracy of the method and optimisation of its implementation.
Chattering free control of continuous‐time switched linear systems
Authors: Deaecto Grace Silva , Souza Matheus , Geromel José C.
Published: March 2014

Chattering is an undesirable phenomenon characterised by infinitely fast switching which may cause equipment damage in real systems. To avoid its occurrence, this study proposes a chattering‐free switching strategy for continuous‐time switched linear systems ensuring global asymptotical stability and a guaranteed cost level associated to the rms gain of a class of input to output signals. The switching function is designed considering a minimum dwell‐time constraint in order to avoid chattering and a maximum one to ensure robustness with respect to sampling jitters and implementation imperfections as, for instance, delays in the switching process. The conditions are based on Riccati–Metzler inequalities which take into account an equivalent discrete‐time switched linear system obtained from the continuous‐time one guided by a sampled switching rule without any kind of approximation. As a new result, for a subclass of Metzler matrices, necessary and sufficient conditions for the existence of a solution for the Riccati–Metzler inequalities are provided. Theoretical aspects are illustrated by some academical examples.
Distributed model predictive control for polytopic uncertain systems with randomly occurring actuator saturation and packet loss
Authors: Song Yan , Fang Xiaosheng
Published: March 2014

In this study, a distributed model predictive control algorithm is presented for the polytopic uncertain system subject to randomly occurring actuator saturation and packet loss. The global system is decomposed into several subsystems, and a novel distributed controller model is established to account for both the actuator saturation and packet loss in a unified representation by using two sets of Bernoulli distributed white sequences with known conditional probabilities. By transforming the non‐linear feedback law into a convex hull of linear feedback laws, the distributed controllers for subsystems are obtained by solving a linear matrix inequality (LMI) optimisation problem. Finally, two simulation examples are employed to show the effectiveness of the techniques proposed in this study.
Coupled cluster channels in the homogeneous electron gas
Authors: Shepherd James J. , Henderson Thomas M. , Scuseria Gustavo E.
Published: March 2014

We discuss diagrammatic modifications to the coupled cluster doubles (CCD) equations, wherein different groups of terms out of rings, ladders, crossed-rings, and mosaics can be removed to form approximations to the coupled cluster method, of interest due to their similarity with various types of random phase approximations. The finite uniform electron gas (UEG) is benchmarked for 14- and 54-electron systems at the complete basis set limit over a wide density range and performance of different flavours of CCD is determined. These results confirm that rings generally overcorrelate and ladders generally undercorrelate; mosaics-only CCD yields a result surprisingly close to CCD. We use a recently developed numerical analysis [J. J. Shepherd and A. Grüneis, Phys. Rev. Lett. 110, 226401 (2013)] to study the behaviours of these methods in the thermodynamic limit. We determine that the mosaics, on forming the Brueckner one-body Hamiltonian, open a gap in the effective one-particle eigenvalues at the Fermi energy. Numerical evidence is presented which shows that methods based on this renormalisation have convergent energies in the thermodynamic limit including mosaic-only CCD, which is just a renormalised MP2. All other methods including only a single channel, namely, ladder-only CCD, ring-only CCD, and crossed-ring-only CCD, appear to yield divergent energies; incorporation of mosaic terms prevents this from happening.
A comparative theoretical study on core-hole excitation spectra of azafullerene and its derivatives
Authors: Deng Yunfeng , Gao Bin , Deng Mingsen , Luo Yi
Published: March 2014

The core-hole excitation spectra—near-edge x-ray absorption spectroscopy (NEXAFS), x-ray emission spectroscopy (XES), and x-ray photoelectron spectroscopy (XPS) shake-up satellites have been simulated at the level of density functional theory for the azafullerene C59N and its derivatives (C59N)+, C59HN, (C59N)2, and C59N–C60, in which the XPS shake-up satellites were simulated using our developed equivalent core hole Kohn-Sham (ECH-KS) density functional theory approach [B. Gao, Z. Wu, and Y. Luo, J. Chem. Phys. 128, 234704 (2008)] which aims for the study of XPS shake-up satellites of large-scale molecules. Our calculated spectra are generally in good agreement with available experimental results that validates the use of the ECH-KS method in the present work. The nitrogen K-edge NEXAFS, XES, and XPS shake-up satellites spectra in general can be used as fingerprints to distinguish the azafullerene C59N and its different derivatives. Meanwhile, different carbon K-edge spectra could also provide detailed information of (local) electronic structures of different molecules. In particular, a peak (at around 284.5 eV) in the carbon K-edge NEXAFS spectrum of the heterodimer C59N–C60 is confirmed to be related to the electron transfer from the C59N part to the C60 part in this charge-transfer complex.
Ferroelectric domain building blocks for photonic and nonlinear optical microstructures in LiNbO3
Authors: Zisis G. , Ying C. Y. J. , Soergel E. , Mailis S.
Published: March 2014

The ability to manipulate the size and depth of poling inhibited domains, which are produced by UV laser irradiation of the +z face of lithium niobate crystals followed by electric field poling, is demonstrated. It is shown that complex domain structures, much wider than the irradiating laser spot, can be obtained by partially overlapping the subsequent UV laser irradiated tracks. The result of this stitching process is one uniform domain without any remaining trace of its constituent components thus increasing dramatically the utility of this method for the fabrication of surface microstructures as well as periodic and aperiodic domain lattices for nonlinear optical and surface acoustic wave applications. Finally, the impact of multi exposure on the domain characteristics is also investigated indicating that some control over the domain depth can be attained.
Domain wall motion in Tb/Co multilayer wires with a large domain wall depinning field
Authors: Bang Do , Awano Hiroyuki
Published: March 2014

We have investigated domain wall (DW) motion in Tb/Co multilayer wires with a large DW depinning field ∼3.0 kOe and different wire widths. In this system, the DW depinning field was decreased as a linear dependence of injecting current. A high effective efficiency ε ∼ 5 × 10−13 T m2 A−1 was obtained. Threshold current density for the DW motion was found to be approximately 3 × 1011 A/m2 for the wires. High DW velocity up to 90 m/s was observed. In addition, the DW velocity showed a strong dependence on perpendicular (easy-axis) magnetic field. These results suggest that the Tb/Co wire is an excellent candidate for the high-speed and stability of stored information in DW-controlled devices.
The category of Yetter-Drinfel'd Hom-modules and the quantum Hom-Yang-Baxter equation
Authors: Chen Yuanyuan , Zhang Liangyun
Published: March 2014

In this paper, we introduce the category of Yetter-Drinfel'd Hom-modules which is a braided monoidal category and show that the category of Yetter-Drinfel'd Hom-modules is a full monoidal subcategory of the left center of left Hom-module category. Also we study the equivalent relationship between the category of Yetter-Drinfel'd Hom-modules and the category of Hom-modules over the Drinfel'd double. Finally, the Faddeev-Reshetikhin-Takhtajan (FRT) type theorem for the quantum Hom-Yang-Baxter equation is investigated.
Few-hole double quantum dot in an undoped GaAs/AlGaAs heterostructure
Authors: Tracy L. A. , Hargett T. W. , Reno J. L.
Published: March 2014

We demonstrate a hole double quantum dot in an undoped GaAs/AlGaAs heterostructure. The interdot coupling can be tuned over a wide range, from formation of a large single dot to two well-isolated quantum dots. Using charge sensing, we show the ability to completely empty the dot of holes and control the charge occupation in the few-hole regime. The device should allow for control of individual hole spins in single and double quantum dots in GaAs.
Growing point-to-set length scales in Lennard-Jones glass-forming liquids
Authors: Li Yan-Wei , Xu Wen-Sheng , Sun Zhao-Yan
Published: March 2014

We study the point-to-set length scales and dynamics in three-dimensional Kob-Andersen glass-forming liquids with amorphous boundary conditions by using molecular dynamics simulation, where a set of particles in an equilibrium configuration are pinned while other particles move as before. We consider three different geometries, i.e., spherical cavity, cubic cavity, and walls, for the pinning set of particles. We present the growing static and dynamic point-to-set correlation length scales in the temperature range higher than the ideal mode-coupling theory transition temperature of the bulk. Our results reveal that the two-point static spatial correlations are almost the same for these three geometries at the same temperature, which implies weak geometry dependence on the structure of such glass-forming liquids. By analyzing z (the distance from the wall) dependent point-to-set overlaps, we find that the particles in the layers near the pinning wall relax slower than those far away from the wall. Associated with the dynamical slowdown, the static length scale increases modestly while the dynamic length scale increases dramatically as the temperature is lowered. Compared with the two cavities, the “Walls” system relaxes faster at the same temperature and the same distance from the wall and has smaller length scales. Moreover, the relation between time scale and static length scales depends on the degree of supercooling and the type of geometries. We did not see any clear evidence for the one-to-one correspondence between static and dynamic point-to-set length scales, and also for the one-to-one correspondence between static length scales and relaxation time in the deep supercooled regime. Our results provide clues for the existence of multi-relaxation modes in the supercooled regime in three-dimensional Kob-Andersen glass-forming liquids.
Note: Simultaneous determination of local temperature and thickness of heated cantilevers using two-wavelength thermoreflectance
Authors: Park Heeseung , Lee Bong Jae , Lee Jungchul
Published: March 2014

In this work, we have demonstrated that two-wavelength thermoreflectance technique can be used to characterize the local thickness and temperature of heated cantilevers at steady-state operation. By taking the ratio of reflectances for two lasers with different wavelengths, the geometrical factor causing the mismatch between experimentally measured and theoretically calculated reflectances was eliminated. Based on the fitting analysis of the reflectance ratio of two wavelengths at various input powers to the heated cantilevers, the local temperature and thickness could be unambiguously determined.
Observation of the inverse spin Hall effect in ZnO thin films: An all-electrical approach to spin injection and detection
Authors: Prestgard Megan C. , Tiwari Ashutosh
Published: March 2014

The inverse spin Hall effect (ISHE) is a newly discovered, quantum mechanical phenomenon where an applied spin current results in the generation of an electrical voltage in the transverse direction. It is anticipated that the ISHE can provide a more simple way of measuring spin currents in spintronic devices. The ISHE was first observed in noble metals that exhibit strong spin-orbit coupling. However, recently, the ISHE has been detected in conventional semiconductors (such as Si and Ge), which possess weak spin-orbit coupling. This suggests that large-spin orbit coupling is not a requirement for observing the ISHE. In this paper, we are reporting the observation of the ISHE in an alternative semiconductor material, zinc oxide (ZnO) using all-electrical means. In our study, we found that when a spin-polarized current is injected into the ZnO film from a NiFe ferromagnetic injector via an MgO tunnel barrier layer, a voltage transverse to both the direction of the current as well as its spin-polarization is generated in the ZnO layer. The polarity of this voltage signal was found to flip on reversing the direction of the injected current as well as on reversing the polarization of the current, consistent with the predictions of the ISHE process. Through careful analysis of the ISHE data, we determined a spin-Hall angle of approximately 1.651 × 10−2 for ZnO, which is two orders of magnitude higher than that of silicon. Observation of a detectable room-temperature ISHE signal in ZnO via electrical injection and detection is a groundbreaking step that opens a path towards achieving transparent spin detectors for next-generation spintronic device technology.
Communication: The influence of CO2 poisoning on overvoltages and discharge capacity in non-aqueous Li-Air batteries
Authors: Mekonnen Yedilfana S. , Knudsen Kristian B. , Mýrdal Jon S. G. , Younesi Reza , Højberg Jonathan , Hjelm Johan , Norby Poul , Vegge Tejs
Published: March 2014

The effects of Li2CO3 like species originating from reactions between CO2 and Li2O2 at the cathode of non-aqueous Li-air batteries were studied by density functional theory (DFT) and galvanostatic charge-discharge measurements. Adsorption energies of CO2 at various nucleation sites on a stepped $({1\bar 100})$(11¯00) Li2O2 surface were determined and even a low concentration of CO2 effectively blocks the step nucleation site and alters the Li2O2 shape due to Li2CO3 formation. Nudged elastic band calculations show that once CO2 is adsorbed on a step valley site, it is effectively unable to diffuse and impacts the Li2O2 growth mechanism, capacity, and overvoltages. The charging processes are strongly influenced by CO2 contamination, and exhibit increased overvoltages and increased capacity, as a result of poisoning of nucleation sites: this effect is predicted from DFT calculations and observed experimentally already at 1% CO2. Large capacity losses and overvoltages are seen at higher CO2 concentrations.
Comparing the line broadened quasilinear model to Vlasov code
Authors: Ghantous K. , Berk H. L. , Gorelenkov N. N.
Published: March 2014

The Line Broadened Quasilinear (LBQ) model is revisited to study its predicted saturation level as compared with predictions of a Vlasov solver BOT [Lilley et al., Phys. Rev. Lett. 102, 195003 (2009) and M. Lilley, BOT Manual. The parametric dependencies of the model are modified to achieve more accuracy compared to the results of the Vlasov solver both in regards to a mode amplitude's time evolution to a saturated state and its final steady state amplitude in the parameter space of the model's applicability. However, the regions of stability as predicted by LBQ model and BOT are found to significantly differ from each other. The solutions of the BOT simulations are found to have a larger region of instability than the LBQ simulations.
Absorption-aided x-ray emission tomography of planar targets
Authors: Stambulchik E. , Kroupp E. , Maron Y. , Zastrau U. , Uschmann I. , Paulus G. G.
Published: March 2014

Suggested is a tomography-like method for studying properties of solid-density plasmas with cylindrical symmetry, such as formed in the interaction of high-power lasers with planar targets. The method is based on simultaneous observation of the target x-ray fluorescence at different angles. It can be applied for validation of existing hypotheses and lately for reconstruction of the plasma properties with three-dimensional resolution. The latter becomes straightforward if the resonance x-ray self-absorption is negligible. The utility of the method is demonstrated by examples.
Influences of electric field on the jitter of ultraviolet-illuminated switch under pulsed voltages
Authors: Li Junna , Chen Weiqing , Chen Zhiqiang , Tang Junping , Jia Wei , Guo Fan , Xie Linshen , Zhang Guowei , Qiu Aici
Published: March 2014

In a wide variety of high-power pulsed facilities, megavolt switches play a key role in determining the system performance. In particular, ultraviolet (UV)-illuminated switches have been widely used for their high-voltage, low-jitter characteristics. In this paper, two factors that may affect the breakdown jitter of a 3 MV UV-illuminated switch under pulsed voltages were investigated, namely, the electric field enhancement factor of a UV-illuminating gap (UV gap) and the number of UV gaps. The experimental results show that the electric field enhancement factor is important for adjusting the average E/p of the main switch gap when the UV gaps breaks down under certain N2 pressures. When the electric field enhancement factor of the UV gaps is approximately that of the main switch gap, the breakdown jitter percentage goes down to less than 1.9%. Comparatively, the number of UV gaps affects breakdown voltage and jitter in a limited-way. When only one UV gap is functioning and the electric field enhancement factor of UV gap is approximately that of the main switch gap, the breakdown jitter is less than 1.3%.
Symmetrical and anti-symmetrical coherent perfect absorption for acoustic waves
Authors: Wei Pengjiang , Croënne Charles , Tak Chu Sai , Li Jensen
Published: March 2014

We investigate tunable acoustic absorption enabled by the coherent control of input waves. It relies on coherent perfect absorption originally proposed in optics. By designing appropriate acoustic metamaterial structures with resonating effective bulk modulus or density, we show that complete absorption of incident waves impinging on the metamaterial can be achieved for either symmetrical or anti-symmetrical inputs in the forward and backward directions. By adjusting the relative phase between the two incident beams, absorption can be tuned effectively from unity to zero, making coherent control useful in applications like acoustic modulators, noise controllers, transducers, and switches.
Carrier dynamics in inhomogeneously broadened InAs/AlGaInAs/InP quantum-dot semiconductor optical amplifiers
Authors: Karni O. , Kuchar K. J. , Capua A. , Mikhelashvili V. , Sęk G. , Misiewicz J. , Ivanov V. , Reithmaier J. P. , Eisenstein G.
Published: March 2014

We report on a characterization of fundamental gain dynamics in recently developed InAs/InP quantum-dot semiconductor optical amplifiers. Multi-wavelength pump-probe measurements were used to determine gain recovery rates, following a powerful optical pump pulse, at various wavelengths for different bias levels and pump excitation powers. The recovery was dominated by coupling between the electronic states in the quantum-dots and the high energy carrier reservoir via capture and escape mechanisms. These processes determine also the wavelength dependencies of gain saturation depth and the asymptotic gain recovery level. Unlike quantum-dash amplifiers, these quantum-dots exhibit no instantaneous gain response, confirming their quasi zero-dimensional nature.
Large penetration depth of near-field heat flux in hyperbolic media
Authors: Lang S. , Tschikin M. , Biehs S.-A. , Petrov A. Yu. , Eich M.
Published: March 2014

We compare super-Planckian thermal radiation between phonon-polaritonic media and hyperbolic metamaterials. In particular, we determine the penetration depth of thermal photons inside the absorbing medium for three different structures: two semi-infinite phonon-polaritonic media supporting surface modes, two multilayer hyperbolic metamaterials and two nanowire hyperbolic metamaterials. We show that for hyperbolic modes the penetration depth can be orders of magnitude larger than for surface modes suggesting that hyperbolic materials are much more preferable for near-field thermophotovoltaic applications than pure phonon-polaritonic materials.
Influence of the pH value of a colloidal gold solution on the absorption spectra of an LSPR-assisted sensor
Authors: Zhu Jin , Li Wenbin , Zhu Mao , Zhang Wei , Niu Wencheng , Liu Guohua
Published: March 2014

The localized surface plasmon resonances (LSPRs) of gold particles assembled on a crystal plate are a powerful tool for biological sensors. Here, we prepare gold colloids in different pH solutions. We monitor the effects of the particle radius and particle coverage on the absorption spectra of AT-cut (r-face dihedral angle of about 3°) crystal plates supporting gold nanoparticles. The surface morphologies were monitored on silicon dioxide substrates using ultraviolet and visible (UV-vis) spectroscopy, and atomic force microscopy (AFM). The results showed that the gold particle coverage decreases with increasing pH value of the gold colloid solution. This phenomenon demonstrates that self-assembled gold surfaces were formed via the electrostatic adsorption of gold particles on the positively charged, ionized amino groups on the crystal plates in the acidic solution. The spectrum of gold nanoparticles with different coverage degree on the crystal plates showed that the LSPR properties are highly dependent on pH.
Piezoresistive measurement of Swine H1N1 Hemagglutinin peptide binding with microcantilever arrays
Authors: Bajwa N. , Maldonado C. J. , Thundat T. , Passian A.
Published: March 2014

Effective detection of Swine H1N1 Hemagglutinin peptide is crucial as it could be used as a positive control to screen for highly infectious flu strains such as Swine-Origin Influenza A (H1N1). Piezoresistive microcantilever arrays present a pathway towards highly sensitive and label-free detection of biomolecules by transducing the antigen-antibody binding into change in resistivity via induced surface stress variation. We demonstrate a mechanical transduction of Swine H1N1 Hemagglutinin peptide binding and suggest the employed technique may offer a potential platform for detection of the H1N1 virus, which could be clinically used to diagnose and provide subsequent relief.
Enhancing DNA binding rate using optical trapping of high-density gold nanodisks
Authors: Lin En-Hung , Pan Ming-Yang , Lee Ming-Chang , Wei Pei-Kuen
Published: March 2014

We present the dynamic study of optical trapping of fluorescent molecules using high-density gold nanodisk arrays. The gold nanodisks were fabricated by electron beam lithography with a diameter of 500 nm and a period of 1 μm. Dark-field illumination showed ∼15 times enhancement of fluorescence near edges of nanodisks. Such enhanced near-field generated an optical trapping force of ∼10 fN under 3.58 × 103 W/m2 illumination intensity as calculated from the Brownian motions of 590 nm polystyrene beads. Kinetic observation of thiolated DNA modified with Cy5 dye showed different binding rates of DNA under different illumination intensity. The binding rate increased from 2.14 × 103 s−1 (I = 0.7 × 103 W/m2) to 1.15 × 105 s−1 (I = 3.58 × 103 W/m2). Both enhanced fluorescence and binding rate indicate that gold nanodisks efficiently improve both detection limit and interaction time for microarrays.
The Chaebol and the US Military—Industrial Complex: Cold War Geopolitical Economy and South Korean Industrialization
Authors: Glassman Jim , Choi Young-Jin
Published: March 2014

Among scholars of East Asia, the role of US military offshore procurement (OSP) and the military–industrial complex (MIC) has been underplayed in explanations of rapid industrial transformation. Yet the foundations of industrialization in places such as South Korea, when analyzed in strongly ‘national–territorial’ and state-centric terms of the predominant, so-called ‘neo-Weberian’ accounts, remain inadequately illuminated. We argue that a geopolitical economy approach focusing on the roles of OSP and relations within the US MIC brings to light crucial sociospatial dimensions of the Korean developmental state's industrial success during the Vietnam War era, dimensions that are largely absent from the neo-Weberian accounts. We examine, in particular, the Park Chung Hee regime's participation in the Vietnam War, and the attendant development of Korean industrial chaebol such as Hyundai, arguing that the successes of the south Korean developmental state and chaebol were enabled by their enrolment in the US MIC, via OSP.
Knowledge discovery by accuracy maximization
Authors: Cacciatore Stefano , Luchinat Claudio , Tenori Leonardo
Published: March 2014

Significance

We propose an innovative method to extract new knowledge from noisy and high-dimensional data. Our approach differs from previous methods in that it has an integrated procedure of validation of the results through maximization of cross-validated accuracy. In many cases, this method performs better than existing feature extraction methods and offers a general framework for analyzing any kind of complex data in a broad range of sciences. Examples ranging from genomics and metabolomics to astronomy and linguistics show the versatility of the method.
Experimental, numerical, and analytical velocity spectra in turbulent quantum fluid
Authors: Barenghi Carlo F. , L’vov Victor S. , Roche Philippe-E.
Published: March 2014

Turbulence in superfluid helium is unusual and presents a challenge to fluid dynamicists because it consists of two coupled, interpenetrating turbulent fluids: the first is inviscid with quantized vorticity, and the second is viscous with continuous vorticity. Despite this double nature, the observed spectra of the superfluid turbulent velocity at sufficiently large length scales are similar to those of ordinary turbulence. We present experimental, numerical, and theoretical results that explain these similarities, and illustrate the limits of our present understanding of superfluid turbulence at smaller scales.
Two-photon microscopy reveals early rod photoreceptor cell damage in light-exposed mutant mice
Authors: Maeda Akiko , Palczewska Grazyna , Golczak Marcin , Kohno Hideo , Dong Zhiqian , Maeda Tadao , Palczewski Krzysztof
Published: March 2014

Significance

Identifying the sequence of events underlying light-induced pathology is important for understanding the mechanisms leading to retinal degeneration, and consequently for development of therapies against retinal diseases. In this study, we characterized the early phase of retinal degeneration using two-photon microscopy, mass spectroscopy, and genetically modified mice. We identified rod photoreceptors as the initial locus of degeneration. Primary changes included retinoid-dependent formation of fluorescent metabolic by-products within rod photoreceptor cells and a nearly three-fold expansion/swelling of rod outer segments. These changes were followed by secondary infiltration of microglia/macrophages to clear photoreceptor cell debris. Finally, we provide evidence that phagocytosis-mediated transfer of rod-derived toxic compounds to the retinal pigmented epithelium is required to elicit damage to that cell layer.
Giant pressure-induced volume collapse in the pyrite mineral MnS
2
Authors: Kimber Simon A. J. , Salamat Ashkan , Evans Shaun R. , Jeschke Harald O. , Muthukumar Kaliappan , Tomić Milan , Salvat-Pujol Francesc , Valentí Roser , Kaisheva Maria V. , Zizak Ivo , Chatterji Tapan
Published: March 2014

Significance

Minerals that contain magnetic metals may collapse under the pressures found in the Earth’s mantle. These so-called spin-state transitions are due to the reduction of the magnetic moment associated with each metal atom. Here we report the discovery of a giant volume collapse in the mineral hauerite (MnS
2
) under pressure. Instead of a change in the single-ion magnetic moments, this is driven by the Mn
2+
cations spontaneously forming pairs, or dimers. In contrast to the magnetic, unpaired electrons found at ambient pressure, the dense new phase contains an ordered arrangement of chemical bonds that are globally nonmagnetic. This “squeezing out” of magnetism is shown to stabilize the huge increase in density.
Deepwater Horizon
crude oil impacts the developing hearts of large predatory pelagic fish
Authors: Incardona John P. , Gardner Luke D. , Linbo Tiffany L. , Brown Tanya L. , Esbaugh Andrew J. , Mager Edward M. , Stieglitz John D. , French Barbara L. , Labenia Jana S. , Laetz Cathy A. , Tagal Mark , Sloan Catherine A. , Elizur Abigail , Benetti Daniel D. , Grosell Martin , Block Barbara A. , Scholz Nathaniel L.
Published: March 2014

Significance

The 2010
Deepwater Horizon
(MC252) disaster in the northern Gulf of Mexico released more than 4 million barrels of crude oil. Oil rose from the ocean floor to the surface where many large pelagic fish spawn. Here we describe the impacts of field-collected oil samples on the rapidly developing embryos of warm-water predators, including bluefin and yellowfin tunas and an amberjack. For each species, environmentally relevant MC252 oil exposures caused serious defects in heart development. Moreover, abnormalities in cardiac function were highly consistent, indicating a broadly conserved developmental crude oil cardiotoxicity. Losses of early life stages were therefore likely for Gulf populations of tunas, amberjack, swordfish, billfish, and other large predators that spawned in oiled surface habitats.
Physical activity when young provides lifelong benefits to cortical bone size and strength in men
Authors: Warden Stuart J. , Mantila Roosa Sara M. , Kersh Mariana E. , Hurd Andrea L. , Fleisig Glenn S. , Pandy Marcus G. , Fuchs Robyn K.
Published: March 2014

Significance

Bones adapt to mechanical forces in youth to increase their size and strength but are more at risk for breaking later in life. Do the skeletal benefits of physical activity in youth persist with aging? Here we show at an upper extremity site that half of the benefit in bone size and one-third of the benefit in bone strength obtained from physical activity during youth are maintained throughout life, even though the bone mass benefits are lost. When physical activity was continued during aging, some mass and more strength benefits were preserved. These data suggest that physical activity during youth should be encouraged for lifelong bone health, with the focus being optimization of bone size rather than increasing mass.
Structural mechanism of serum amyloid A-mediated inflammatory amyloidosis
Authors: Lu Jinghua , Yu Yadong , Zhu Iowis , Cheng Yifan , Sun Peter D.
Published: March 2014

Significance

Serum amyloid A (SAA) is a major serum acute-phase protein and a cause of secondary amyloidosis, which impacts ∼1% of patients with chronic inflammation such as rheumatoid arthritis and neoplastic diseases. The lack of structural information has hampered our understanding of SAA-mediated amyloidosis and the development of effective therapies. Here we report a crystal structure of human SAA1.1 as a prototypic member of the family. SAA1.1 exists as a hexamer with subunits displaying a unique four-helix bundle fold. We further defined binding sites for heparin and high-density lipoprotein, identified major amyloidogenic epitopes, and visualized SAA-mediated protofibril formation using electron microscopy. These studies provide mechanistic insights into amyloidogenic conformational transition of SAA.
Extended lifespan and reduced adiposity in mice lacking the FAT10 gene
Authors: Canaan Allon , DeFuria Jason , Perelman Eddie , Schultz Vincent , Seay Montrell , Tuck David , Flavell Richard A. , Snyder Michael P. , Obin Martin S. , Weissman Sherman M.
Published: March 2014

Significance

For the first time we describe a physiological role for HLA-F adjacent transcript 10 (FAT10) in metabolism, obesity, and aging in mammals. We show that FAT10 knockout prevents the development of age-associated obesity in mice while extending lifespan and vigor without the appearance of deleterious developmental effects. In addition, we did not observe an increase in cancer incidence. If the role of FAT10 in humans is similar to mice, then targeting of FAT10 may hold promising therapeutic impact for the treatment of various diseases including obesity and obesity-related diseases and aging associated diseases.
Low-dose recombinant properdin provides substantial protection againstStreptococcus pneumoniaeandNeisseria meningitidisinfection
Authors: Ali Youssif Mohammed , Hayat Azam , Saeed Bayad Mawlood , Haleem Kashif S. , Alshamrani Saleh , Kenawy Hany I. , Ferreira Viviana P. , Saggu Gurpanna , Buchberger Anna , Lachmann Peter J. , Sim Robert B. , Goundis Dimitrios , Andrew Peter W. , Lynch Nicholas J. , Schwaeble Wilhelm J.
Published: March 2014

Significance

This paper describes the successful therapeutic application of properdin, a positive regulator of complement activation. Recombinant expression of properdin generated a highly polymerized artificial form of properdin, Pn, with significantly higher functional activity than the lower-grade properdin polymers in serum. Adding low pharmacologic quantities of Pnto serum markedly enhanced complement deposition onNeisseria meningitidisandStreptococcus pneumoniaeand dramatically boosted serum lysis of meningococci. In mouse models of infection for these two major human pathogens, a single low-dose application of Pnsignificantly reduced bacteremia and markedly increased survival rates. Interestingly, therapeutic induction of massive complement mediated lysis of meningococci did not induce septic shock symptoms through the release of bacterial toxins.
Regional brain responses associated with drinking water during thirst and after its satiation
Authors: Saker Pascal , Farrell Michael J. , Adib Faiz R. M. , Egan Gary F. , McKinley Michael J. , Denton Derek A.
Published: March 2014

Significance

Drinking water in response to thirst following fluid loss is a pleasant experience, whereas drinking water after thirst has been satiated is unpleasant. The pleasantness of drinking when thirsty is associated with activation in the anterior cingulate cortex and orbitofrontal region. The unpleasantness and aversion of overdrinking is associated with activations in the midcingulate cortex, insula, amygdala, and periaqueductal grey. Activations in the putamen and cerebellum, and also in the motor cortex, possibly reflect volitional effort to conduct compliant drinking in the face of mechanisms inhibiting intake. These regions may contribute to the termination of drinking. Overdrinking with hyponatraemia and cerebral edema can occur in schizophrenia, reflecting that this brain disorder can derange physiological mechanisms regulating water balance.