bluuebunny/crossref_metadata_2025 huggingface dataset:
A green recycling process designed for LiFePO4 cathode materials for Li-ion batteries
Authors: Shin Eun Jeong , Kim Soo , Noh Jae-Kyo , Byun Dongjin , Chung Kyung Yoon , Kim Hyung-Sun , Cho Byung-Won
Published: April 2015

A green process route is proposed to recycle LiFePO4 cathode materials from FePO4·2H2O metastrengite I intermediate phase.
A biomimetic 3D microtubule-orientated poly(lactide-co-glycolide) scaffold with interconnected pores for tissue engineering
Authors: Shen Hong , Niu Yuguang , Hu Xixue , Yang Fei , Wang Shenguo , Wu Decheng
Published: April 2015

We constructed microtubule-orientated PLGA scaffolds with interconnected pores by an improved thermal-induced phase separation technique using a mixed solvent of 1,4-dioxane and water.
Multi-modal sensing in spin crossover compounds
Authors: Gentili Denis , Demitri Nicola , Schäfer Bernhard , Liscio Fabiola , Bergenti Ilaria , Ruani Giampiero , Ruben Mario , Cavallini Massimiliano
Published: April 2015

We demonstrate multi-modal sensing capabilities of short chain alcohols of spin crossover compounds by integrating them into a micrometric TAG sensitive to the colour and birefringence.
Decision‐tree‐based human activity classification algorithm using single‐channel foot‐mounted gyroscope
Authors: McCarthy M.W. , James D.A. , Lee J.B. , Rowlands D.D.
Published: April 2015

Wearable devices that measure and recognise human activity in real time require classification algorithms that are both fast and accurate when implemented on limited hardware. A decision‐tree‐based method for differentiating between individual walking, running, stair climbing and stair descent strides using a single channel of a foot‐mounted gyroscope suitable for implementation on embedded hardware is presented. Temporal features unique to each activity were extracted using an initial subject group (n = 13) and a decision‐tree‐based classification algorithm was developed using the timing information of these features. A second subject group (n = 10) completed the same activities to provide data for verification of the system. Results indicate that the classifier was able to correctly match each stride to its activity with >90% accuracy. Running and walking strides in particular matched with >99% accuracy. The outcomes demonstrate that a lightweight yet robust classification system is feasible for implementation on embedded hardware for real‐time daily monitoring.
Using dispersive delay lines and time reversal for low contrast tumour detection
Authors: Zhou Hong‐Cheng , Fusco Vincent , Wang Bing‐Zhong , Zhong Lei , Ding Shuai , Zhao De‐Shuang
Published: April 2015

On the basis of the technique of time reversal (TR), through adding dispersive delay lines to each element of a TR mirror, a method for low contrast tumour detection is proposed. When compared with a conventional detection method, the proposed method improves refocusing onto a low dielectric contrast tumour. The method does not require an accurate estimate of the position of the tumour. The theoretical basis for the approach is given and numerical simulated results demonstrate the capability of the proposed method.
Algorithm for power angle control to improve power quality in distribution system using unified power quality conditioner
Authors: Ansari Abdul Quaiyum , Singh Bhim , Hasan Mashhood
Published: April 2015

A novel algorithm is proposed for power angle control (PAC) to improve power quality (PQ) in distribution system. This algorithm reduces mathematical complication and its response time. It has aimed to make the designs of controller. The new concept is incorporates on triangle rules of vector addition/subtraction. The mathematical approach makes the algorithm efficient and comprehensive. The shunt voltage source converter (VSC) of unified power quality conditioner (UPQC) is controlled using instantaneous symmetrical component theory (ISCT). The ISCT enables UPQC to handle unbalanced and non‐linear loads. The complete phaser diagram has been shown for various voltage conditions. A vector addition and subtraction‐based mathematical calculation has been derived for estimation of different parameters of the proposed system. Proposed PAC can improve PQ in four wire distribution system with maximum utilisation of series VSC of UPQC. A simulation study for voltage sag/swell with the new algorithm for PAC verifies the improved performance of the system. Results have been discussed in detail.
Review of pedestrian detection techniques in automotive far‐infrared video
Authors: Hurney Patrick , Waldron Peter , Morgan Fearghal , Jones Edward , Glavin Martin
Published: April 2015

The use of advanced driver assistance systems is becoming increasingly common in road‐going vehicles. One application of these driver assistance systems is in the automated detection of vulnerable road users, such as pedestrians, using automotive far‐infrared imagery. Detection of pedestrians in infrared imagery can be quite difficult because of a number of factors such as the environment, pedestrian behaviour and also the physical limitations of currently available infrared sensors. This study presents a comprehensive review of the literature currently available in the area of pedestrian detection techniques in automotive infrared imagery. The challenges associated with automated detection of pedestrians in the automotive domain are first discussed. An overview of the general structure of pedestrian detection algorithms is then presented, followed by an in‐depth analysis of existing literature in the area. Some proposals for future research in the area based on the methods described in this study are then offered.
Optimal design of a class‐E resonant driver
Authors: Evzelman Michael , Peretz Mor Mordechai
Published: April 2015

In many applications of class‐E converters, custom‐made design of the isolation resonant network is impractical; instead, off‐shelf products are used. In this case, matching the target output parameters to the converter component stresses requires an additional passive matching network. The design of this network has a tedious optimisation routine and may pose a considerable engineering challenge. This study introduces an optimisation method based on a behavioural modelling for class‐E resonant converters, which significantly simplifies the component selection procedure. The method reduces the number of unknowns during simulation assisted parameter optimisation search. Successful implementation of the optimisation process is demonstrated on an off‐line, digitally controlled class‐E, piezoelectric transformer‐based AC/DC converter, where the main inductor and the matching capacitance are the parameters to be optimised.
Indirect vector control with simplified rotor resistance adaptation for induction machines
Authors: Kan Jingbo , Zhang Kai , Wang Ze
Published: April 2015

A novel indirect vector control system for induction machines is proposed. To ensure accurate rotor flux orientation in face of severe thermal drift of the rotor resistance during practical operation, the system features a new rotor resistance adaptation method. The latter is based on the elimination of the q‐axis rotor flux, which is calculated from steady‐state relations of the induction machine. Compared with other rotor resistance adaptation methods found in the literature, for example, observer‐based and model reference adaptive system‐based methods, the proposed one poses much less computation burden and is quite convenient for online implementation. The basic principle and theoretical analysis are presented. The effects of other motor parameters on the adaptation method are also investigated. Based on the investigation results, a stator resistance compensation algorithm is incorporated to reduce the impact of incorrect stator resistance at low speeds. Some non‐negligible issues in practical applications, such as dead‐time effect and transport delay of digital pulse‐width modulation process, are also investigated and taken care of. Simulation and experimental results show good dynamic and steady‐state performance.
Formulation of phase voltage and calculation of its total harmonic distortion in multilevel Z‐source inverter
Authors: Shid Pilehvar Mohsen , Mardaneh Mohammad , Rajaei Amirhossein
Published: April 2015

Multilevel inverters have recently been received more attention in the power industry. Two traditional types of multilevel inverters are multilevel voltage‐source inverter and multilevel current‐source inverter. Despite this widespread use, multilevel Z‐source inverter (ML‐ZSI) has not been regarded enough, because a unique approach to voltage control of ML‐ZSI has not yet been presented. Besides, the phase voltage and its total harmonic distortion (THD) have not been calculated for ML‐ZSI so far. This study proposes two new methods for the formulation of phase voltage in ML‐ZSI. The first method is based on Fourier series analysis of the phase‐voltage waveform, and the second utilises the staircase waveform of the phase voltage. In addition, two new methods are introduced for computing the phase‐voltage THD in ML‐ZSI: approximate method and waveform‐integration method. Although the waveform‐integration method leads to the accurate answer, using this method is more difficult than an approximate method. The detailed description of suggested methods and comparison with each other are presented in this study. Simulation and experimental results are also given to demonstrate the new features of the proposed methods.
Modified scalar discontinuous pulse‐width modulation method for two‐level three‐wire voltage source inverters under unbalanced and distorted conditions
Authors: Shayestehfard Alireza , Mekhilef Saad , Mokhlis Hazlie
Published: April 2015

The discontinuous pulse‐width modulation (DPWM) method is well known and has a wide range of applications. This method uses phase values as reference signals. DPWM modulator improves the inverter efficiency and linearity range, while a poor inverter output is experienced at lower modulation indices. Under unbalanced and distorted conditions, online conversion of line‐to‐line values into phase values is not possible. However, the line‐to‐line voltages are measurable in any application. The proposed technique is the first scalar method that directly uses line‐to‐line voltages as reference signals. A modified DPWM method that shows better performance characteristics is introduced for three‐phase three‐wire two‐level voltage source inverters. The proposed method achieves the maximum possible output voltage with an appreciable performance in terms of harmonic distortion and switching losses without injecting a zero‐sequence signal. Therefore, the method is referred as implicit zero‐sequence DPWM (IZDPWM). IZDPWM was verified under balanced, unbalanced and distorted conditions in both simulation and experimental testes. Simulation and experimental results demonstrate the validity and the performance of the proposed method.
Coordinated radar resource management for networked phased array radars
Authors: Moo Peter W. , Ding Zhen
Published: April 2015

A phased array radar has the ability to rapidly and adaptively position beams and adjust dwell times, thus enabling a single radar to perform multiple functions, such as surveillance, tracking and fire control. A radar resource manager prioritises and schedules tasks from the various functions to best use available resources. Networked phased array radars that are connected by a communication channel are studied. This study considers whether coordinated radar resource management (RRM), which exploits the sharing of tracking and detection data between radars, enhances performance compared with independent RRM. Two types of distributed management techniques for coordinated RRM are proposed, with each type characterised by varying amounts of coordination between the radars. A two‐radar network and 30‐target scenario are modelled in the simulation tool Adapt_MFR, to analyse the performance of the two coordinated RRM techniques against the baseline case of independent RRM. Results indicate that the coordinated RRM techniques achieve the same track completeness as independent RRM, while decreasing track occupancy and frame time. Therefore, coordinated RRM can improve reaction time against threats, at the expense of sending data across a communication channel. The performance of coordinated RRM for a communication channel with errors is also modelled and analysed.
High resolution range profile of compressive sensing radar with low computational complexity
Authors: Li Hongtao , Wang Chaoyu , Wang Ke , He Yapeng , Zhu Xiaohua
Published: April 2015

On the basis of compressive sensing radar, this study presents a new method of reconstructing the moving target's high‐resolution range profile (HRRP) with low computational complexity. With regard to the spatial sparsity of the radar scene, only a few sub‐pulses of frequency‐stepped chirp signal (FSCS) are used to sample the target's frequency responses. To reduce the computational complexity of traditional compressive sensing (CS) algorithm which uses FSCS to reconstruct moving target's HRRP, a dynamically deduced sensing matrix is established based on target's velocity estimation. Besides, the orthogonality of the deduced sensing matrix is analysed from the perspective of FSCS frequency encoding types to enhance the HRRP construction accuracy using CS algorithms. Numerical simulations demonstrate that the proposed method performs better than traditional algorithm with smaller estimation error and better robustness against noise.
Laparoskopischer Bruchlückenverschluss bei Appendizitis im Leistenhernienbruchsack (Amyand-Hernie): Ist der Einsatz eines Netzes kontraindiziert?
Authors: Scheidbach H. , Blume B. , Meyer F.
Published: April 2015

Die Amyand-Hernie wird definiert als eine Appendix vermiformis mit oder ohne Entzündung im Bruchsack einer ipsilateralen Leistenhernie. Die Inzidenz dieser Sonderform einer Leistenhernie ist außerordentlich selten und präsentiert sich präoperativ nahezu ausschließlich unter dem Bild einer inkarzerierten Leistenhernie. Der Einsatz von synthetischen Netzen bei der Versorgung derartiger Hernien wird kontrovers diskutiert und überwiegend abgelehnt. Im Zeitalter der dominierend prothetischen Hernienversorgung stellt sich die Frage der simultanen Netzimplantation bei potenzieller Kontamination neu. Anhand der 150 bislang zu diesem Thema veröffentlichten Fälle und ihrer detaillierten Analyse wird versucht, eine Neubewertung der Frage des Bruchlückenverschlusses mit Netz bei der Amyand-Hernie, nicht zuletzt basierend auf eigenen fallspezifischen Erfahrungen, darzulegen. Auch beim intraoperativen Zufallsbefund einer Appendizitis im Bruchsack einer Leistenhernie kann eine laparoskopische Hernienversorgung unter Verwendung eines Netzes nach simultaner Appendektomie, wie geplant, erfolgen, sofern eine Mitresektion des adhärenten Bruchsacks vorgenommen wird. Falls synthetische Implantate benutzt werden, sollten zwingend ausschließlich leichtgewichtige und großporige Netze zum Einsatz kommen.
Transcutaneous Drainage of Gel-Like Substance after Application of Hydrogel Dural Sealant: Report of Two Cases
Authors: Siman Homayoun , Techy Fernando
Published: April 2015

Study Design

Case report.

Objective

Incidental durotomy (IDT) is a common complication of spinal surgery. The use of collagen matrix graft along with hydrogel dural sealant is a common method of IDT repair. With this method, there have been several reported cases of detrimental dural sealant expansion in the literature. One case study reported an expansion rate greater than 300%; many report neurologic damage. This article reports the clinical course of two patients who developed postoperative transcutaneous drainage of a gel-like substance after the use of a dural sealant, which is a previously unreported complication.

Methods

The clinical course and treatment outcome of two patients is presented.

Results

Both patients experienced postoperative transcutaneous drainage of a gel-like substance at the surgical site. Case one began draining this substance on postoperative day 14. This patient required no further intervention, and the drainage ended after 3 mL of a gel-like substance was expressed from his incision while in the clinic. Case two began draining the gel on postoperative day 16. This patient underwent two washout procedures and resolution of the drainage. No infection was ever detected.

Conclusions

To our knowledge, our patients are the first reported cases of transcutaneous drainage of expanded dural sealant. It is important to take into consideration the unexpected expansion of a dural sealant when using it for the repair of IDT.
Traumatic Migration of the Bryan Cervical Disc Arthroplasty
Authors: Wagner Scott C. , Kang Daniel G. , Helgeson Melvin D.
Published: April 2015

Study Design

Case study.

Objective

To describe a case of dislodgment and migration of the Bryan Cervical Disc (Medtronic Sofamor Danek, Memphis, Tennessee, United States) arthroplasty more than 6 months after implantation secondary to low-energy trauma.

Methods

The inpatient, outpatient, and radiographic medical records of a patient with traumatic migration of the Bryan Cervical Disc arthroplasty were reviewed. The authors have no relevant disclosures to report.

Results

A 36-year-old man with chronic left upper extremity radiculopathy underwent uncomplicated Bryan Cervical Disc arthroplasty at C5–C6, with complete resolution of his symptoms. Approximately 6 months after his index procedure, he sustained low-energy trauma to the posterior cervical spine, after being struck by a book falling from a shelf. The injury forced his neck into flexion, and though he did not have recurrence of his radiculopathy symptoms, radiographs demonstrated anterior migration of the arthroplasty device. He underwent revision to anterior cervical diskectomy and fusion.

Conclusions

Although extremely rare, it is imperative that surgeons consider the potential for failure of osseous integration in patients undergoing cervical disk arthroplasty, even beyond 3 to 6 months postoperatively. This concern is especially relevant to press-fit or milled devices like the Bryan Cervical Disc arthroplasty, which lack direct fixation into adjacent vertebral bodies. We are considering modification of our postoperative protocol to improve protection of the device after implantation, even beyond 3 months postoperatively.
Mixtures of ions and amphiphilic molecules in slit-like pores: A density functional approach
Authors: Pizio O. , Rżysko W. , Sokołowski S. , Sokołowska Z.
Published: April 2015

We investigate microscopic structure and thermodynamic properties of a mixture that contains amphiphilic molecules and charged hard spheres confined in slit-like pores with uncharged hard walls. The model and the density functional approach are the same as described in details in our previous work [Pizio et al., J. Chem. Phys. 140, 174706 (2014)]. Our principal focus is in exploring the effects brought by the presence of ions on the structure of confined amphiphilic particles. We have found that for some cases of anisotropic interactions, the change of the structure of confined fluids occurs via the first-order transitions. Moreover, if anions and cations are attracted by different hemispheres of amphiphiles, a charge at the walls appears at the zero value of the wall electrostatic potential. For a given thermodynamic state, this charge is an oscillating function of the pore width.
Connes distance function on fuzzy sphere and the connection between geometry and statistics
Authors: Devi Yendrembam Chaoba , Prajapat Shivraj , Mukhopadhyay Aritra K. , Chakraborty Biswajit , Scholtz Frederik G.
Published: April 2015

An algorithm to compute Connes spectral distance, adaptable to the Hilbert-Schmidt operatorial formulation of non-commutative quantum mechanics, was developed earlier by introducing the appropriate spectral triple and used to compute infinitesimal distances in the Moyal plane, revealing a deep connection between geometry and statistics. In this paper, using the same algorithm, the Connes spectral distance has been calculated in the Hilbert-Schmidt operatorial formulation for the fuzzy sphere whose spatial coordinates satisfy the su(2) algebra. This has been computed for both the discrete and the Perelemov’s SU(2) coherent state. Here also, we get a connection between geometry and statistics which is shown by computing the infinitesimal distance between mixed states on the quantum Hilbert space of a particular fuzzy sphere, indexed by n ∈ ℤ/2.
Experimental evidence of skyrmion-like configurations in bilayer nanodisks with perpendicular magnetic anisotropy
Authors: Stebliy Maxim E. , Kolesnikov Alexander G. , Davydenko Alexander V. , Ognev Alexey V. , Samardak Alexander S. , Chebotkevich Ludmila A.
Published: April 2015

Formation and existence of magnetic skyrmion-like configurations in bilayer nanodisks {Ta(3 nm)/[Co(0.37 nm)/Ni(0.58 nm)]10}2 with perpendicular magnetic anisotropy are shown experimentally at room temperature. Magnetization reversal through the skyrmion state is studied using magnetic hysteresis measurements. An evolution of skyrmion configurations in the nanodisk structure is analyzed. Experimental methods and micromagnetic simulations help to understand the magnetization reversal processes occurring through the stable skyrmion-like configurations. Formation of the intermediate C-states during magnetization reversal is demonstrated. The skyrmion number for all possible spin configurations is calculated.
Emergence of kinetic behavior in streaming ultracold neutral plasmas
Authors: McQuillen P. , Castro J. , Bradshaw S. J. , Killian T. C.
Published: April 2015

We create streaming ultracold neutral plasmas by tailoring the photoionizing laser beam that creates the plasma. By varying the electron temperature, we control the relative velocity of the streaming populations, and, in conjunction with variation of the plasma density, this controls the ion collisionality of the colliding streams. Laser-induced fluorescence is used to map the spatially resolved density and velocity distribution function for the ions. We identify the lack of local thermal equilibrium and distinct populations of interpenetrating, counter-streaming ions as signatures of kinetic behavior. Experimental data are compared with results from a one-dimensional, two-fluid numerical simulation.
Perturbations around the zeros of classical orthogonal polynomials
Authors: Sasaki Ryu
Published: April 2015

Starting from degree N solutions of a time dependent Schrödinger-like equation for classical orthogonal polynomials, a linear matrix equation describing perturbations around the N zeros of the polynomial is derived. The matrix has remarkable Diophantine properties. Its eigenvalues are independent of the zeros. The corresponding eigenvectors provide the representations of the lower degree (0,1,…,N−1) polynomials in terms of the zeros of the degree N polynomial. The results are valid universally for all the classical orthogonal polynomials, including the Askey scheme of hypergeometric orthogonal polynomials and its q-analogues.
Compositional modulated atomic layer stacking and uniaxial magnetocrystalline anisotropy of CoPt alloy sputtered films with close-packed plane orientation
Authors: Saito Shin , Nozawa Naoki , Hinata Shintaro , Takahashi Migaku , Shibuya Kazunari , Hoshino Kazuya , Awaya Satoru
Published: April 2015

An atomic layer stacking structure in hexagonal close packed (hcp) Co100−xPtx alloy films with c-plane sheet texture was directly observed by a high-angle annular dark-field imaging scanning transmission electron microscopy. The analysis of sequential and/or compositional atomic layer stacking structure and uniaxial magnetocrystalline anisotropy (Ku = Ku1 + Ku2) revealed that (1) integrated intensity of the superlattice diffraction takes the maximum at x = 20 at. % and shows broadening feature against x for the film fabricated under the substrate temperature (Tsub) of 400 °C. (2) Compositional separation structure in atomic layers is formed for the films fabricated under Tsub = 400 °C. A sequential alternative stacking of atomic layers with different compositions is hardly formed in the film with x = 50 at. %, whereas easily formed in the film with x = 20 at. %. This peculiar atomic layer stacking structure consists of in-plane-disordered Pt-rich and Pt-poor layers, which is completely different from the so-called atomic site ordered structure. (3) A face centered cubic atomic layer stacking as faults appeared in the host hcp atomic layer stacking exists in accompanies with irregularities for the periodicity of the compositional modulation atomic layers. (4) Ku1 takes the maximum of 1.4 × 107 erg/cm3 at around x = 20 at. %, whereas Ku2 takes the maximum of 0.7 × 107 erg/cm3 at around x = 40 at. %, which results in the maximum of 1.8 × 107 erg/cm3 of Ku at x = 30 at. % and a shoulder in compositional dependence of Ku in the range of x = 30–60 at. %. Not only compositional separation of atomic layers but also sequential alternative stacking of different compositional layers is quite important to improve essential uniaxial magnetocrystalline anisotropy.
Fault ride-through capability improvement of doubly fed induction generator-based wind turbine using static volt ampere reactive compensator
Authors: Safaei Arman , Vahidi Behrooz , Hosseinian Seyed Hossein , Abyaneh Hossein Askarian
Published: April 2015

The use of wind energy is increasing due to rapid increase in energy consumption and rapid deployment of wind energy. Among different types of wind turbine generators, doubly fed induction generators are most widely used because of their low cost and capability to work in different wind speeds. On the other hand, doubly fed induction generators (DFIGs) are very sensitive to voltage drop. If a fault occurs in the network the voltage of DFIG terminal drops. So the rotor current increases and this may lead to damage DFIG converters. So, a protection system must be used to protect DFIG converters. One of the common schemes used to protect DFIGs is crowbar protection. In this paper, the effects of static volt ampere reactive compensator (SVC) on DFIG operation during voltage drop and crowbar protection are investigated in detail. Results show that by using SVC the voltage drop of DFIG terminal during grid faults decreases. Therefore, the operation time of crowbar decreases and the fault ride through capability of DFIG increases.
Practical method using superposition of individual magnetic fields for initial arrangement of undulator magnets
Authors: Tsuchiya K. , Shioya T.
Published: April 2015

We have developed a practical method for determining an excellent initial arrangement of magnetic arrays for a pure-magnet Halbach-type undulator. In this method, the longitudinal magnetic field distribution of each magnet is measured using a moving Hall probe system along the beam axis with a high positional resolution. The initial arrangement of magnetic arrays is optimized and selected by analyzing the superposition of all distribution data in order to achieve adequate spectral quality for the undulator. We applied this method to two elliptically polarizing undulators (EPUs), called U#16-2 and U#02-2, at the Photon Factory storage ring (PF ring) in the High Energy Accelerator Research Organization (KEK). The measured field distribution of the undulator was demonstrated to be excellent for the initial arrangement of the magnet array, and this method saved a great deal of effort in adjusting the magnetic fields of EPUs.
Ultraviolet photochemical reaction of [Fe(III)(C2O4)3]3− in aqueous solutions studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser
Authors: Ogi Y. , Obara Y. , Katayama T. , Suzuki Y.-I. , Liu S. Y. , Bartlett N. C.-M. , Kurahashi N. , Karashima S. , Togashi T. , Inubushi Y. , Ogawa K. , Owada S. , Rubešová M. , Yabashi M. , Misawa K. , Slavíček P. , Suzuki T.
Published: April 2015

Time-resolved X-ray absorption spectroscopy was performed for aqueous ammonium iron(III) oxalate trihydrate solutions using an X-ray free electron laser and a synchronized ultraviolet laser. The spectral and time resolutions of the experiment were 1.3 eV and 200 fs, respectively. A femtosecond 268 nm pulse was employed to excite [Fe(III)(C2O4)3]3− in solution from the high-spin ground electronic state to ligand-to-metal charge transfer state(s), and the subsequent dynamics were studied by observing the time-evolution of the X-ray absorption spectrum near the Fe K-edge. Upon 268 nm photoexcitation, the Fe K-edge underwent a red-shift by more than 4 eV within 140 fs; however, the magnitude of the redshift subsequently diminished within 3 ps. The Fe K-edge of the photoproduct remained lower in energy than that of [Fe(III)(C2O4)3]3−. The observed red-shift of the Fe K-edge and the spectral feature of the product indicate that Fe(III) is upon excitation immediately photoreduced to Fe(II), followed by ligand dissociation from Fe(II). Based on a comparison of the X-ray absorption spectra with density functional theory calculations, we propose that the dissociation proceeds in two steps, forming first [(CO2•)Fe(II)(C2O4)2]3− and subsequently [Fe(II)(C2O4)2]2−.
Magnetization switching of a metallic nanomagnet via current-induced surface spin-polarization of an underlying topological insulator
Authors: Roy Urmimala , Dey Rik , Pramanik Tanmoy , Ghosh Bahniman , Register Leonard F. , Banerjee Sanjay K.
Published: April 2015

We consider a thermally stable, metallic nanoscale ferromagnet (FM) subject to spin-polarized current injection and exchange coupling from the spin-helically locked surface states of a topological insulator (TI) to evaluate possible non-volatile memory applications. We consider parallel transport in the TI and the metallic FM, and focus on the efficiency of magnetization switching as a function of transport between the TI and the FM. Transport is modeled as diffusive in the TI beneath the FM, consistent with the mobility in the TI at room temperature, and in the FM, which essentially serves as a constant potential region albeit spin-dependent except in the low conductivity, diffusive limit. Thus, it can be captured by drift-diffusion simulation, which allows for ready interpretation of the results. We calculate switching time and energy consumed per write operation using self-consistent transport, spin-transfer-torque (STT), and magnetization dynamics calculations. Calculated switching energies and times compare favorably to conventional spin-torque memory schemes for substantial interlayer conductivity. Nevertheless, we find that shunting of current from the TI to a metallic nanomagnet can substantially limit efficiency. Exacerbating the problem, STT from the TI effectively increases the TI resistivity. We show that for optimum performance, the sheet resistivity of the FM layer should be comparable to or larger than that of the TI surface layer. Thus, the effective conductivity of the FM layer becomes a critical design consideration for TI-based non-volatile memory.
Harmonic generation by circularly polarized laser beams propagating in plasma
Authors: Agrawal Ekta , Hemlata  , Jha Pallavi
Published: April 2015

An analytical theory is developed for studying the phenomenon of generation of harmonics by the propagation of an obliquely incident, circularly polarized laser beam in homogeneous, underdense plasma. The amplitudes of second and third harmonic radiation as well as detuning distance have been obtained and their variation with the angle of incidence is analyzed. The amplitude of harmonic radiation increases with the angle of incidence while the detuning distance decreases, for a given plasma electron density. It is observed that the generated second and third harmonic radiation is linearly and elliptically polarized, respectively. The harmonic radiation vanishes at normal incidence of the circularly polarized laser beam.
Magnetic resonant wireless power transfer for propulsion of implantable micro-robot
Authors: Kim D. , Kim M. , Yoo J. , Park H.-H. , Ahn S.
Published: April 2015

Recently, various types of mobile micro-robots have been proposed for medical and industrial applications. Especially in medical applications, a motor system for propulsion cannot easily be used in a micro-robot due to their small size. Therefore, micro-robots are usually actuated by controlling the magnitude and direction of an external magnetic field. However, for micro-robots, these methods in general are only applicable for moving and drilling operations, but not for the undertaking of various missions. In this paper, we propose a new micro-robot concept, which uses wireless power transfer to deliver the propulsion force and electric power simultaneously. The mechanism of Lorentz force generation and the coil design methodologies are explained, and validation of the proposed propulsion system for a micro-robot is discussed thorough a simulation and with actual measurements with up-scaled test vehicles.
Hydrodynamics of a self-actuated bacterial carpet using microscale particle image velocimetry
Authors: Kim Hoyeon , Cheang U Kei , Kim Dalhyung , Ali Jamel , Kim Min Jun
Published: April 2015

Microorganisms can effectively generate propulsive force at the microscale where viscous forces overwhelmingly dominate inertia forces; bacteria achieve this task through flagellar motion. When swarming bacteria, cultured on agar plates, are blotted onto the surface of a microfabricated structure, a monolayer of bacteria forms what is termed a “bacterial carpet,” which generates strong flows due to the combined motion of their freely rotating flagella. Furthermore, when the bacterial carpet coated microstructure is released into a low Reynolds number fluidic environment, the propulsive force of the bacterial carpet is able to give the microstructure motility. In our previous investigations, we demonstrated motion control of these bacteria powered microbiorobots (MBRs). Without any external stimuli, MBRs display natural rotational and translational movements on their own; this MBR self-actuation is due to the coordination of flagella. Here, we investigate the flow fields generated by bacterial carpets, and compare this flow to the flow fields observed in the bulk fluid at a series of locations above the bacterial carpet. Using microscale particle image velocimetry, we characterize the flow fields generated from the bacterial carpets of MBRs in an effort to understand their propulsive flow, as well as the resulting pattern of flagella driven self-actuated motion. Comparing the velocities between the bacterial carpets on fixed and untethered MBRs, it was found that flow velocities near the surface of the microstructure were strongest, and at distances far above, the surface flow velocities were much smaller.
Effects of magnetic fields on dissolution of arthritis causing crystals
Authors: Takeuchi Y. , Iwasaka M.
Published: April 2015

The number of gout patients has rapidly increased because of excess alcohol and salt intake. The agent responsible for gout is the monosodium urate (MSU) crystal. MSU crystals are found in blood and consist of uric acid and sodium. As a substitute for drug dosing or excessive water intake, physical stimulation by magnetic fields represents a new medical treatment for gout. In this study, we investigated the effects of a magnetic field on the dissolution of a MSU crystal suspension. The white MSU crystal suspension was dissolved in an alkaline solution. We measured the light transmission of the MSU crystal suspension by a transmitted light measuring system. The magnetic field was generated by a horizontal electromagnet (maximum field strength was 500 mT). The MSU crystal suspension that dissolved during the application of a magnetic field of 500 mT clearly had a higher dissolution rate when compared with the control sample. We postulate that the alkali solution promoted penetration upon diamagnetic rotation and this magnetic field orienting is because of the pronounced diamagnetic susceptibility anisotropy of the MSU crystal. The results indicate that magnetic fields represent an effective gout treatment approach.
Characterization of the magnetic moment distribution in low-concentration solutions of iron oxide nanoparticles by a high-Tc superconducting quantum interference device magnetometer
Authors: Saari M. M. , Sakai K. , Kiwa T. , Sasayama T. , Yoshida T. , Tsukada K.
Published: April 2015

We developed a highly sensitive AC/DC magnetometer using a high-temperature superconductor superconducting quantum interference device for the evaluation of magnetic nanoparticles in solutions. Using the developed system, we investigated the distribution of magnetic moments of iron oxide multi-core particles of 100 nm at various iron concentrations that are lower than 96 μg/ml by analyzing the measured magnetization curves. Singular value decomposition and non-regularized non-negative least-squares methods were used during the reconstruction of the distribution. Similar distributions were obtained for all concentrations, and the iron concentration could be determined from the measured magnetization curves. The measured harmonics upon the excitation of AC and DC magnetic fields curves agreed well with the harmonics simulated based on the reconstructed magnetization curves, implying that the magnetization curves of magnetic nanoparticles were successfully obtained as we will show in the article. We compared the magnetization curves between multi-core particles of 100 nm and 130 nm, composed of 12-nm iron oxide nanoparticles. A distinctive magnetic property between the 100 nm and 130 nm particles in low-concentration solutions was successfully characterized. The distribution characteristic of magnetic moments suggests that the net magnetic moment in a multi-core particle is affected by the size of the magnetic cores and their degree of aggregation. Exploration of magnetic properties with high sensitivity can be expected using the developed system.
Perpendicular exchange bias behaviors of CoPt/IrMn and CoPt/FeMn bilayers: A comparative study
Authors: Tsai C. Y. , Hsu Jen-Hwa , Lin K. F.
Published: April 2015

In this study, FeMn was introduced as an antiferromagnetic (AFM) layer to couple with a single-layered Co49Pt51 alloy thin film, and it was compared with a Co49Pt51/IrMn bilayer system in exchange bias (EB) effect, to explore the mechanism of spontaneous perpendicular exchange bias (PEB), which has been recently observed in CoPt/IrMn bilayers. Bilayers of CoPt/IrMn and CoPt/FeMn were prepared under the same conditions by sputtering at room temperature without any inducing field. Although PEB was observed in as-grown CoPt/FeMn bilayers, the loop shape and PEB behavior were found to exhibit different characteristics from those of CoPt/IrMn bilayers. The CoPt (5 nm)/FeMn (10 nm) bilayer has a sheared loop that is similar to a double-shifted loop and a much lower squareness ratio (SQR = 0.52) and exchange bias field (He = 180 Oe) than the CoPt (5 nm)/IrMn (10 nm) system, which has a rectangular loop shape and a high SQR of 0.97 and large He of 290 Oe. The two systems present entirely different dependences of PEB on the thickness of the AFM layer. CoPt/IrMn exhibits behavior that is typical of most EB systems, but for CoPt/FeMn, this dependence is more complicated with an unusual peak at an AFM layer thickness of 10 nm. Based on the dissimilar loop shapes and dependences of PEB on AFM thickness, the mechanisms of the spontaneously established PEB in these two systems are considered to differ. Investigations of cross-sectional transmission electron microscopy revealed no apparent difference between the interfacial microstructures of the two systems. X-ray diffraction studies demonstrated the ⟨111⟩ texture of both systems. Therefore, different interfacial spin configurations may be responsible for the dissimilar PEB behaviors in these two FM/AFM bilayer systems.
On the structural origins of ferroelectricity in HfO2 thin films
Authors: Sang Xiahan , Grimley Everett D. , Schenk Tony , Schroeder Uwe , LeBeau James M.
Published: April 2015

Here, we present a structural study on the origin of ferroelectricity in Gd doped HfO2 thin films. We apply aberration corrected high-angle annular dark-field scanning transmission electron microscopy to directly determine the underlying lattice type using projected atom positions and measured lattice parameters. Furthermore, we apply nanoscale electron diffraction methods to visualize the crystal symmetry elements. Combined, the experimental results provide unambiguous evidence for the existence of a non-centrosymmetric orthorhombic phase that can support spontaneous polarization, resolving the origin of ferroelectricity in HfO2 thin films.
Multipeak self-biased magnetoelectric coupling characteristics in four-phase Metglas/Terfenol-D/Be-bronze/PMN-PT structure
Authors: Huang Dongyan , Lu Caijiang , Bing Han
Published: April 2015

This letter develops a self-biased magnetoelectric (ME) structure Metglas/Terfenol-D/Be-bronze/PMN-PT (MTBP) consisting of a magnetization-graded Metglas/Terfenol-D layer, a elastic Be-bronze plate, and a piezoelectric 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) plate. By using the magnetization-graded Metglas/Terfenol-D layer and the elastic Be-bronze plate, multi-peak self-biased ME responses are obtained in MTBP structure. The experimental results show that the MTBP structure with two layers of Metglas foil has maximum zero-biased ME voltage coefficient (MEVC). As frequency increases from 0.5 to 90 kHz, eleven large peaks of MEVC with magnitudes of 0.75-33 V/(cm Oe) are observed at zero-biased magnetic field. The results demonstrate that the proposed multi-peak self-biased ME structure may be useful for multifunctional devices such as multi-frequency energy harvesters or low-frequency ac magnetic field sensors.
From manufacturing belt, to rust belt, to college country: a visual narrative of US urban growth
Authors: Arribas-Bel Daniel , Gerritse Michiel
Published: April 2015

What has shaped the US urban landscape? Probably, different forces worked at different magnitudes, times, and locations. In this paper we develop a methodology to disaggregate some of the engines of US city growth over time and across space. To understand the results we propose a visualization approach based on what we term storyboards, which create an intuitive and dynamic narrative on the effect of several factors of urban success. This allows us to show that the role of growth engines differs greatly: the rise and decline of manufacturing were very localized; industrial specialization is counterproductive, particularly so in the 1990s; service sectors used to be a consumption amenity, but now serve as a production amenity; and highly educated cities unambiguously and increasingly attract firms in any part of the US. We also note that the arguments for our visualization and its lessons bear implications for visualization in the social sciences beyond this particular example.
Individuals’ spatial social network choice: model-based analysis of leisure-contact selection
Authors: Kowald Matthias , Arentze Theo A , Axhausen Kay W
Published: April 2015

Leisure travel holds an important share of the overall amount of travel. However, efforts in transport planning to model and explain leisure travel have been rather limited for a long time. Only recently, a subcommunity of researchers began to use the methods of social network analysis. Existing research in this area, however, has focused on social interaction behaviour of individuals given their social networks. The selection of friends underlying the generation of social networks has received less attention. To fill this gap, our aims in this study are a descriptive analysis of leisure network data, and specification and estimation of a utility-based friendship-decision model. Data on connected personal leisure networks are obtained by using the personal network approach in an extended survey framework. Results offer insights into the decision of who is in contact with whom and which combinations of attributes have either an increasing or decreasing effect on the utility of a leisure relationship. The model can be used to simulate social network generation in an agent-based travel-demand simulation and with that enable the consideration of relevant behavioural patterns in the simulation of leisure trips.
Mapping policies and programmes: the use of GIS to communicate spatial relationships in England
Authors: Wong Cecilia , Baker Mark , Webb Brian , Hincks Stephen , Schulze-Baing Andreas
Published: April 2015

It has long been acknowledged that there is a gap between the advancement of GIS in the research field and its application in planning practice. This paper demonstrates the potential for employing simple GIS mapping overlays as a way of communicating complex planning issues in a ‘language’ that is easily understandable and effective at stimulating policy debate, critical thinking, and learning. The analysis focuses on capturing the synergies and conflicts in two key planning challenges in England, progrowth and housing delivery agendas. In a political context where spatial evidence-based policy making has been eroded in recent years, the analysis demonstrates the need for policy makers to ‘think spatially, act spatially’ when developing different policies and programmes. The paper concludes that only by making spatial relationships of policies and programmes explicit in a manner that is easily understood by a range of actors, can different spatial scenarios and metaphors of future opportunities and challenges be developed to inform long-range development and planning.
Head-to-head antisense transcription and R-loop formation promotes transcriptional activation
Authors: Boque-Sastre Raquel , Soler Marta , Oliveira-Mateos Cristina , Portela Anna , Moutinho Catia , Sayols Sergi , Villanueva Alberto , Esteller Manel , Guil Sonia
Published: April 2015

Significance

The molecular mechanisms used by noncoding RNAs to regulate gene expression are largely unknown. We have discovered a previously unidentified regulatory phenomenon underlying the transcriptional activation of the intermediate filament protein vimentin. This regulation involves the participation of a previously uncharacterized head-to-head antisense transcript that forms part of a hybrid DNA:RNA structure known as the R loop. R loops have been the focus of recent research regarding their unexpected involvement in gene expression regulation. Antisense-mediated formation of the R loop supports a local chromatin environment that ensures the optimal binding of vimentin transcriptional activators. In addition, we describe how hypermethylation of the locus in a large panel of colon cancer patients is correlated with antisense silencing and, thereby, compromises its regulatory activity.
Inferring epigenetic dynamics from kin correlations
Authors: Hormoz Sahand , Desprat Nicolas , Shraiman Boris I.
Published: April 2015

Significance

Different cells in a clonal population can be in different phenotypic states, which persist for a few generations before switching to another state. Dynamics of switching between these states determines the extent of correlations between the phenotypes of related cells. Here we demonstrate—using ideas from statistical physics—that it is possible to infer simple stochastic dynamics along lineages from an instantaneous measurement of phenotypic correlations in a cell population with defined genealogy. The approach is validated using experimental observations on
Pseudomonas aeruginosa
colonies.
Prior categorization can produce more efficient ordering
Authors: Kemp Simon , Grace Randolph C.
Published: April 2015

We hypothesized that prior categorization of an attribute might sometimes facilitate the ordering of stimuli, particularly when the number of stimuli is relatively large or some of them need to be remembered. In four experiments, participants were required to rank order either numbers or line lengths either using a selection sort or following prior categorization. The results indicated that prior categorization produced faster sorting when the number of stimuli to be ordered was relatively large and when the stimuli were not continuously visible.